tag:theconversation.com,2011:/us/topics/toxins-4350/articlesToxins – The Conversation2024-03-05T16:05:39Ztag:theconversation.com,2011:article/2246642024-03-05T16:05:39Z2024-03-05T16:05:39ZWe’re a step closer to having a universal antivenom for snake bites – new study<p>If you’re bitten by a venomous snake, the medicine you need is antivenom. Unfortunately, antivenoms are species specific, meaning you need to have the right antivenom for the snake that bit you. Most of the time, people have no idea what species of snake has bitten them. And for some snakes, antivenoms are simply not available. </p>
<p><a href="https://www.science.org/doi/full/10.1126/scitranslmed.adk1867">New research</a> my colleagues and I conducted provides a significant step forward in enabling the development of an antivenom that will neutralise the effects of venom from any venomous snake: a so-called “universal antivenom”. </p>
<p>In our paper, published in Science Translational Medicine, we describe the discovery and development of a laboratory-made antibody that can neutralise a neurotoxin (a toxin that acts on the nervous system) found in the venom of many types of snake around the world.</p>
<p>Venomous snakes kill as many as <a href="https://www.who.int/news-room/fact-sheets/detail/snakebite-envenoming#:%7E:text=An%20estimated%205.4%20million%20people,are%20caused%20by%20snakebites%20annually.">138,000 people</a> each year, with many more survivors suffering from life-changing injuries and mental trauma. Children and farmers make up the bulk of the victims. </p>
<p>The active ingredients in antivenoms are anti-toxin antibodies. They are made by injecting horses with small quantities of snake venom and harvesting the antibodies. This method of making antivenom has remained the same for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9634357/#b0005">over a century</a> – and it has substantial drawbacks. </p>
<p>In addition to antivenoms being species specific, they are also not very potent, so you need lots of antivenom to neutralise the venom from a bite. </p>
<p>Also, because antivenoms are made in horses, you are highly likely to experience severe side-effects when administered, as your body’s immune system will detect and react to the “foreign” horse antibodies circulating in your bloodstream. </p>
<p>Antibodies that are made in the laboratory using genetically modified cells are routinely used in humans to treat <a href="https://www.cancer.gov/about-cancer/treatment/types/immunotherapy/monoclonal-antibodies#how-do-monoclonal-antibodies-work-against-cancer">cancers</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8775886/">immune disorders</a>. A long-held hope is that the technology used to produce these antibodies can be used to make antivenom and eventually replace traditional antivenoms, thereby solving many of the issues current antivenoms face.</p>
<p>The antibodies in lab-made antivenoms could be “humanised”, a process that tricks your immune system into thinking foreign antibodies are your own antibodies. This might reduce the rate of severe side-effects that are commonly encountered with horse-derived antivenoms. </p>
<h2>Paralysis and death avoided</h2>
<p>One of the most important families of toxins in snake venoms are neurotoxins. </p>
<p>These toxins prevent nerve signals from travelling from your brain to your muscles, paralysing them. This includes paralysing the muscles that inflate and deflate your lungs, so prey and human victims quickly stop breathing and die. </p>
<p>These neurotoxins are in the venoms of some of the world’s most deadly snakes, including the African black mamba, the Asian monocled cobra and king Cobra, and the deadly kraits of the Indian subcontinent. </p>
<p>In our research, we describe the discovery and development of a lab-made humanised antibody that can neutralise key venom neurotoxins from diverse snakes from diverse regions. </p>
<p>The lab-made antibody is called 95Mat5 and was discovered after examining 50 billion unique antibodies to find ones capable of not only recognising the neurotoxin in the venoms of many species but also able to neutralise its deadly effects. </p>
<p>When injected into mice that had received lethal doses of venom, 95Mat5 was able to prevent paralysis and death in all the venoms tested. </p>
<p>These results are particularly exciting as they show that generating lab-made antibodies that can broadly neutralise the effects of venoms from many species is feasible, making the development of a universal antivenom a realistic prospect. </p>
<p>However, 95Mat5 is a single antibody that only works against neurotoxins. As we said earlier, to make a universal antivenom you will require a handful of antibodies. This is because snake venoms don’t just consist of neurotoxins. </p>
<p>Some snake venoms have haemotoxins, which make you bleed, and some have cytotoxins, which destroy skin and bone. To create a universal antivenom, capable of treating any bite from any snake, we still need to identify additional antibodies that can broadly and potently neutralise the other toxin types, in the same manner as 95Mat5. </p>
<p>We hope that once identified, these antibodies can be mixed with 95Mat5 to make an antivenom that is capable of neutralising the venom of any snake, no matter what toxin types it possesses. </p>
<figure class="align-center ">
<img alt="Person milking a snake" src="https://images.theconversation.com/files/579412/original/file-20240303-24-3b1s50.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579412/original/file-20240303-24-3b1s50.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579412/original/file-20240303-24-3b1s50.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579412/original/file-20240303-24-3b1s50.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579412/original/file-20240303-24-3b1s50.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579412/original/file-20240303-24-3b1s50.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579412/original/file-20240303-24-3b1s50.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A universal antivenom would make milking snakes a thing of the past.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/milking-cobra-snake-venom-thailand-1580384338">Ali _Cobanoglu/Shutterstock</a></span>
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</figure>
<p>The requirement for antibodies for other venom toxins and also the need to ensure any new lab-made antivenom for effectiveness and safety in human trials means it will still take many years for a universal antivenom to become available to snakebite victims. </p>
<p>Other hurdles need to be overcome. These new antivenoms will probably need to be stored in a fridge to prevent loss of effectiveness, so it will need to be shown that they can be distributed in often warm regions of the world that don’t have reliable electricity for refrigeration. </p>
<p>Lab-made antibodies are some of the most expensive drugs on the planet. While we are hopeful, it remains to be seen if lab-made antivenoms will be affordable for most snakebite victims, who are usually some of the poorest people in the world.</p><img src="https://counter.theconversation.com/content/224664/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stuart Ainsworth receives funding from United Kingdom Research and Innovation and the National Centre for the Replacement, Reduction and Refinement of Animals in Research. </span></em></p><p class="fine-print"><em><span>Camille Abada receives funding from the Medical Research Council, UK.</span></em></p>We’re still using century-old technology to make snake antivenom. A method fit for the 21st century is on the horizon.Stuart Ainsworth, Senior Lecture and UKRI Future Leader Fellow, University of LiverpoolCamille Abada, PhD Candidate, Antibodies, Liverpool School of Tropical MedicineLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2116572023-09-14T12:30:25Z2023-09-14T12:30:25ZThe importance of shining a light on hidden toxic histories<figure><img src="https://images.theconversation.com/files/548169/original/file-20230913-23-64mqmc.jpg?ixlib=rb-1.1.0&rect=0%2C4%2C2927%2C1970&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Activists in Newark, N.J., offer tours that teach visitors about the city's legacy of industrial pollution and environmental racism.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-aerial-view-of-newark-new-jersey-shows-smoke-news-photo/635229321?adppopup=true">Charles Rotkin/Corbis via Getty Images</a></span></figcaption></figure><p>Indianapolis proudly claims <a href="https://www.wthr.com/article/entertainment/hoosiers-remember-elvis-presley-indianapolis-concert-amid-new-movie-buzz/531-503bd6a9-c645-4704-bfad-7577126aaad6">Elvis’ last concert</a>, <a href="https://www.youtube.com/watch?v=A2kWIa8wSC0">Robert Kennedy’s speech</a> in response to Martin Luther King Jr.’s assassination, and the Indianapolis 500. There’s a 9/11 memorial, a <a href="https://www.indianawarmemorials.org/explore/medal-of-honor-memorial/">Medal of Honor Memorial</a> and a statue of former NFL quarterback Peyton Manning.</p>
<p>What few locals know, let alone tourists, is that the city also houses one of the largest dry cleaning <a href="https://www.epa.gov/superfund/what-superfund">Superfund sites</a> in the U.S.</p>
<p>From 1952 to 2008, Tuchman Cleaners laundered clothes <a href="https://www.doi.org/10.3389/fpubh.2021.638082">using perchloroethylene</a>, or PERC, a neurotoxin and possible carcinogen. Tuchman operated a chain of cleaners throughout the city, which sent clothes to a facility on Keystone Avenue for cleaning. It was also the location where used solution was stored in underground tanks.</p>
<p>Inspectors noted the presence of volatile organic compounds from leaking tanks and possible spills as early as 1989. By 1994, an underground plume had spread to a nearby aquifer. By the time the EPA became involved in 2011, the <a href="https://response.epa.gov/site/site_profile.aspx?site_id=7130">underground chemical plume</a> had seeped more than a mile underneath a residential area, reaching a well that supplies drinking water to the city.</p>
<p>When geographer <a href="https://liberalarts.iupui.edu/departments/geography/directory/owen-dwyer/">Owen Dwyer</a>, earth scientist <a href="https://science.iupui.edu/people-directory/people/filippelli-gabriel.html">Gabe Filippelli</a> and I investigated and wrote about the social and environmental <a href="https://www.taylorfrancis.com/chapters/oa-edit/10.4324/9781003365259-24/dirty-laundry-toxic-heritage-dry-cleaning-indianapolis-indiana-elizabeth-kryder-reid-owen-dwyer-gabriel-filippelli?context=ubx&refId=242e9f98-2f2d-4587-9449-99734e77a875">history of dry cleaning in Indianapolis</a>, we were struck by how few people outside of the dry cleaning and environmental management fields were aware of this environmental damage. </p>
<p>There are no markers or memorials. There is no mention of it – or any other accounts of contamination – in Indianapolis’ many museums. This kind of silence has been called “<a href="https://www.orionmagazine.org/article/environmental-amnesia/">environmental amnesia</a>” or “<a href="https://www.jstor.org/stable/24906248">collective forgetting</a>.”</p>
<p>Societies celebrate heroes and commemorate tragedies. But where in public memory is environmental harm? What if people thought about it not only as a science or policy problem, but also as a part of history? Would it make a difference if pollution, along with biodiversity loss and climate change, was seen as part of our shared heritage? </p>
<h2>The slow violence of contamination</h2>
<p>Environmental harm often takes place gradually and out of sight, and this could be one reason why there’s so little public conversation and commemoration. In 2011, Princeton English professor <a href="https://www.hup.harvard.edu/catalog.php?isbn=9780674072343">Rob Nixon</a> came up with a term for this kind of environmental degradation: slow violence. </p>
<p>As underground storage tanks leak, <a href="https://www.taylorfrancis.com/chapters/oa-edit/10.4324/9781003365259-10/ghost-wrecks-anthropocene-enduring-toxic-legacy-pacific-war-matthew-carter-ashley-meredith-augustine-kohler-ranger-walter-bill-jeffrey-paul-heersink?context=ubx&refId=9df11100-ce32-4e00-b590-5b9769b00df2">shipwrecks corrode</a>, coal ash ponds seep and <a href="https://www.taylorfrancis.com/chapters/oa-edit/10.4324/9781003365259-6/toxic-heritage-forever-confronting-pfas-contamination-toxicity-lived-experience-thomas-pearson-daniel-renfrew?context=ubx&refId=ef6c0e6a-b9da-4008-9689-9a43a2dc3055">forever chemicals spread</a>, the creeping pace of poisoned soil and water fails to garner the attention that more dramatic environmental disasters attract.</p>
<p>Certain interests benefit from hiding the costs of pollution and its remediation. Sociologists <a href="https://www.russellsage.org/publications/sites-unseen">Scott Frickel and James R. Elliott</a> have studied urban pollution, and they highlight three reasons for its pervasiveness and persistence. </p>
<p>First, in cities, small factories, auto repair shops, dry cleaners and other light industries sometimes only stay open for a decade or two, making it challenging to regulate them and track their environmental impacts over time. By the time contamination is discovered, many facilities have long been shuttered or purchased by new owners. And the polluters have a direct financial interest in not being connected with it, since they could be held liable and forced to pay for cleanup.</p>
<p>Similarly, urban neighborhoods tend to have shifting demographics, and local residents are often not aware of historical pollution. </p>
<p>Finally, it can simply be politically expedient to look the other way and ignore the consequences of pollution. Cities may be concerned that publicizing toxic histories discourage investment and depress property values, and politicians are hesitant to fund projects that may have a long-term benefit but short-term costs. Indianapolis, for example, tried for decades to avoid mitigating the raw sewage flowing into the White River and Fall Creek, arguing it was too expensive to deal with. Only when required by a <a href="https://www.epa.gov/sites/default/files/2013-09/documents/indy0610-cd.pdf">consent decree</a> did the city start to address the problem.</p>
<p>Toxic legacies are also difficult to track because their effects may be hidden by distance and time. Anthropologist Peter Little <a href="https://global.oup.com/academic/product/burning-matters-9780190934552?cc=us&lang=en&">traced the outsourcing of electronics waste recycling</a>, which is shipped from the places where electronics are bought and used, to countries such as Ghana, where labor is cheap and environmental regulations lax. </p>
<p>Then there are the toxic traces of military conflicts, which linger long after the fighting has stopped and troops have returned home. Historian and geologist Daniel Hubé has documented <a href="https://doi.org/10.1080/19475020.2017.1393347">the long-term environmental impact of World War I munitions</a>. </p>
<p>At the end of the war, unused and unexploded bombs and chemical weapons had to be disposed of. In France, at a site known as <a href="https://www.taylorfrancis.com/chapters/oa-edit/10.4324/9781003365259-25/cleaning-battlefields-times-war-polluted-soils-times-peace-case-study-silent-visible-toxic-legacy-great-war-daniel-hub%C3%A9-tobias-bausinger?context=ubx&refId=630129c7-e447-48fd-a959-24bf0bae1d83">Place à Gaz</a>, hundreds of thousands of chemical weapons were burned. Today, the soils have been found to have extraordinarily high levels of arsenic and other heavy metals. </p>
<p>More than a century after the end of the war, little grows on the contaminated, barren land.</p>
<h2>Toxic tours and teaching moments</h2>
<p>There’s a growing movement to make toxic histories more visible.</p>
<p>In Providence, Rhode Island, artist Holly Ewald founded the <a href="http://www.upparts.org/">Urban Pond Procession</a> to call attention to Mashapaug Pond, which was contaminated by <a href="https://medallicartcollector.com/gorham.shtml">a Gorham Silver factory</a>. She worked with community partners to create wearable sculptures, puppets and giant fish, all of which were carried and worn in an annual parade that took place from 2008 to 2017.</p>
<figure class="align-center ">
<img alt="People march along a sidewalk playing instruments and holding signs featuring fish." src="https://images.theconversation.com/files/548175/original/file-20230913-3869-qv2hbs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548175/original/file-20230913-3869-qv2hbs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=415&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548175/original/file-20230913-3869-qv2hbs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=415&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548175/original/file-20230913-3869-qv2hbs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=415&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548175/original/file-20230913-3869-qv2hbs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=522&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548175/original/file-20230913-3869-qv2hbs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=522&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548175/original/file-20230913-3869-qv2hbs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=522&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The Urban Pond Procession took place each summer for 10 years in Providence, R.I.</span>
<span class="attribution"><span class="source">Photo by Mary Beth Meehan, UPP Collection, Providence Public Library</span></span>
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<p>Cultural anthropologist Amelia Fiske collaborated with artist Jonas Fischer to create the graphic novel “<a href="https://utorontopress.com/9781487509538/toxic/">Tóxico</a>,” which will be published in 2024. It depicts petroleum pollution in the Ecuadorian Amazon, as well as the struggles of those fighting for environmental justice. </p>
<p>Toxic tours can educate the public about the histories, causes and consequences of environmental harm. For example, <a href="https://www.taylorfrancis.com/chapters/oa-edit/10.4324/9781003365259-31/environmental-justice-tours-transformative-narratives-struggle-solidarity-activism-ana-isabel-baptista?context=ubx&refId=7e43d2ce-0c5c-41a4-a9b6-40ce10c0848c">Ironbound Community Corporation</a> in Newark, New Jersey, offers a tour of severely contaminated sites, such as the location of the former <a href="https://www.nytimes.com/1998/11/08/nyregion/newark-s-toxic-tomb-six-acres-fouled-dioxin-agent-orange-s-deadly-byproduct.html">Agent Orange factory</a>, where the sediment in the sludge is laced with the carcinogen dioxin. The tour also goes by a detention center <a href="https://www.epa.gov/brownfields/overview-epas-brownfields-program">that’s built on a brownfield</a>, which has only undergone industrial-level remediation because that’s the standard all prisons are held to.</p>
<p>In 2017, the <a href="https://www.humanitiesactionlab.org/">Humanities Action Lab</a> organized “<a href="https://climatesofinequality.org/">Climates of Inequality</a>,” a traveling exhibit co-curated by more than 20 universities and local partners exploring environmental issues affecting communities around the world. The <a href="https://www.taylorfrancis.com/chapters/oa-edit/10.4324/9781003365259-34/toxic-heritage-reparations-activating-memory-environmental-climate-justice-liz-%C5%A1ev%C4%8Denko?context=ubx&refId=e2e664c7-b4d9-4497-b4a4-6d4f5dd1b009">exhibit</a> brings attention to polluted waterways, the impacts of climate change, ecological damage on Indigenous lands and the ways in which immigrant agricultural workers experience heat stress and chronic pesticide exposure. The exhibits also explore the affected communities’ resilience and advocacy.</p>
<p>These stories of pollution and contamination, and their effects on people’s health and livelihoods, represent only a sampling of current efforts to curate toxic heritage. As sociologist Alice Mah writes in her foreword to “<a href="https://www.routledge.com/Toxic-Heritage-Legacies-Futures-and-Environmental-Injustice/Kryder-Reid-May/p/book/9781032429977">Toxic Heritage</a>”: “Reckoning with toxic heritage is an urgent collective task. It is also unsettling work. It requires confronting painful truths about the roots of toxic injustice with courage, honesty, and humility.”</p>
<p>I see public commemoration of hidden toxic histories as a way to push back against denial, habituation and amnesia. It creates a space for public conversation, and it opens up possibilities for a more just and sustainable future.</p><img src="https://counter.theconversation.com/content/211657/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Kryder-Reid receives funding from Indiana University and the Fulbright Program.</span></em></p>Societies celebrate heroes and commemorate tragedies. But why is there so little public acknowledgment of environmental disasters?Elizabeth Kryder-Reid, Chancellor's Professor of Anthropology and Museum Studies, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2104622023-08-10T20:00:53Z2023-08-10T20:00:53ZWhat’s in vapes? Toxins, heavy metals, maybe radioactive polonium<figure><img src="https://images.theconversation.com/files/541174/original/file-20230804-29-77kck2.jpg?ixlib=rb-1.1.0&rect=1%2C1%2C997%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-girl-smokes-disposable-electronic-cigarette-1943062066">Shutterstock</a></span></figcaption></figure><p>If you asked me what’s in e-cigarettes, disposable vapes or e-liquids, my short answer would be “we don’t fully know”.</p>
<p>The huge and increasing range of products and flavours on the market, changes to ingredients when they are heated or interact with each other, and inadequate labelling make this a complicated question to answer.</p>
<p><a href="https://www.annualreviews.org/doi/pdf/10.1146/annurev-anchem-061318-115329">Analytical chemistry</a>, including <a href="https://www.mja.com.au/journal/2022/216/1/chemical-analysis-fresh-and-aged-australian-e-cigarette-liquids">my own team’s research</a>, gives some answers. But understanding the health impacts adds another level of complexity. E-cigarettes’ risk to health varies depending on <a href="https://pubs.acs.org/doi/abs/10.1021/acs.chemrestox.1c00070">many factors</a> including which device or flavours are used, and how people use them.</p>
<p>So vapers just don’t know what they’re inhaling and cannot be certain of the health impacts.</p>
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Read more:
<a href="https://theconversation.com/no-vapes-arent-95-less-harmful-than-cigarettes-heres-how-this-decade-old-myth-took-off-203039">No, vapes aren't 95% less harmful than cigarettes. Here's how this decade-old myth took off</a>
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<h2>What do we know?</h2>
<p>Despite these complexities, there are some consistencies between what different laboratories find.</p>
<p>Ingredients include nicotine, flavouring chemicals, and the liquids that carry them – primarily propylene glycol and glycerine.</p>
<p><a href="https://www.industrialchemicals.gov.au/sites/default/files/2020-08/Non-nicotine%20liquids%20for%20e-cigarette%20devices%20in%20Australia%20chemistry%20and%20health%20concerns%20%5BPDF%201.21%20MB%5D.pdf">Concerningly</a>, we also find volatile organic compounds, particulate matter and carcinogens (agents that can cause cancer), many of which we know are harmful. </p>
<p>Our <a href="https://www.mja.com.au/journal/2019/210/3/nicotine-and-other-potentially-harmful-compounds-nicotine-free-e-cigarette">previous</a> <a href="https://www.mja.com.au/journal/2022/216/1/chemical-analysis-fresh-and-aged-australian-e-cigarette-liquids">research</a> also found 2-chlorophenol in about half of e-liquids users buy to top-up re-fillable e-cigarettes. This is one example of a chemical with no valid reason to be there. Globally, it’s <a href="https://pubchem.ncbi.nlm.nih.gov/compound/2-Chlorophenol#section=Hazard-Classes-and-Categories">classified</a> as “harmful if inhaled”. Its presence is likely due to contamination during manufacturing.</p>
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Read more:
<a href="https://theconversation.com/many-e-cigarette-vaping-liquids-contain-toxic-chemicals-new-australian-research-169615">Many e-cigarette vaping liquids contain toxic chemicals: new Australian research</a>
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<h2>How about polonium?</h2>
<p>One potential ingredient that has been in the news in recent weeks is radioactive polonium-210, the same substance used to <a href="https://theconversation.com/litvinenko-poisoning-polonium-explained-53514">assassinate</a> former Russian spy Alexander Litvinenko in 2006. The Queensland government is <a href="https://www.abc.net.au/news/2023-07-26/queensland-scientists-test-vapes-for-polonium-210/102564282">now testing</a> vapes for it.</p>
<p>Polonium-210 <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9207432/">can be found</a> in traditional cigarettes and other tobacco products. That’s because tobacco plants <a href="https://www.science.org/doi/abs/10.1126/science.153.3738.880">absorb it</a> and other radioactive materials from the soil, air and high-phosphate fertiliser.</p>
<p>Whether polonium-210 is found in aerosols produced by e-cigarettes remains to be seen. Although it is feasible if the glycerine in e-liquids comes from plants and similar fertilisers are used to grow them.</p>
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<strong>
Read more:
<a href="https://theconversation.com/litvinenko-poisoning-polonium-explained-53514">Litvinenko poisoning: polonium explained</a>
</strong>
</em>
</p>
<hr>
<h2>It’s not just the ingredients</h2>
<p>Aside from their ingredients, the materials e-cigarette devices are made from can end up in our bodies.</p>
<p><a href="https://ehp.niehs.nih.gov/doi/full/10.1289/EHP2175">Toxic metals</a> and <a href="https://ehp.niehs.nih.gov/doi/full/10.1289/EHP5686">related substances</a> such as arsenic, lead, chromium and nickel can be detected in both e-liquids and vapers’ urine, saliva and blood.</p>
<p>These substances can pose serious health risks (such as being carcinogenic). They can leach from several parts of an e-cigarette, including the heating coil, wires and soldered joints.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541152/original/file-20230804-21381-h5ifyj.jpg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C655&q=45&auto=format&w=1000&fit=clip"><img alt="Colourful, disposable vapes on a blue background" src="https://images.theconversation.com/files/541152/original/file-20230804-21381-h5ifyj.jpg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C655&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541152/original/file-20230804-21381-h5ifyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=394&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541152/original/file-20230804-21381-h5ifyj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=394&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541152/original/file-20230804-21381-h5ifyj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=394&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541152/original/file-20230804-21381-h5ifyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=495&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541152/original/file-20230804-21381-h5ifyj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=495&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541152/original/file-20230804-21381-h5ifyj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=495&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chemicals from the device itself can end up in our blood, urine and saliva.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/set-colorful-disposable-electronic-cigarettes-on-2065547126">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-asked-over-700-teens-where-they-bought-their-vapes-heres-what-they-said-190669">We asked over 700 teens where they bought their vapes. Here's what they said</a>
</strong>
</em>
</p>
<hr>
<h2>That’s not all</h2>
<p>The process of heating e-liquids to create an inhalable aerosol also changes their chemical make-up to produce <a href="https://pubs.acs.org/doi/10.1021/acs.chemrestox.9b00410">degradation</a> <a href="https://pubs.acs.org/doi/10.1021/acs.est.7b02205">products</a>. </p>
<p>These include:</p>
<ul>
<li><p>formaldehyde (a substance used to embalm dead bodies)</p></li>
<li><p>acetaldehyde (a key substance that contributes to a hangover after drinking alcohol)</p></li>
<li><p>acrolein (used as a chemical weapon in the first world war and now used as a herbicide).</p></li>
</ul>
<p>These chemicals are <a href="https://www.mdpi.com/2305-6304/10/12/714">often detected</a> in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6129974">e-cigarette samples</a>. However due to different devices and how the samples are collected, the <a href="https://ehjournal.biomedcentral.com/articles/10.1186/s12940-017-0249-x">levels measured</a> <a href="https://pubs.acs.org/doi/10.1021/acs.est.7b02205">vary widely</a> between studies.</p>
<p>Often, the levels are very low, leading to proponents of vaping arguing e-cigarettes are far safer than tobacco smoking. </p>
<p>But this argument does not acknowledge that many e-cigarette users (particularly adolescents) <a href="https://www.tobaccoinaustralia.org.au/chapter-18-e-cigarettes/18-3-extent">were or are not cigarette smokers</a>, meaning a better comparison is between e-cigarette use and breathing “fresh” air. </p>
<p>An e-cigarette user is undoubtedly exposed to more toxins and harmful substances than a non-smoker. People who buy tobacco cigarettes are also confronted with a plethora of warnings about the hazards of smoking, while vapers generally are not.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sex-and-lies-are-used-to-sell-vapes-online-even-we-were-surprised-at-the-marketing-tactics-we-found-200446">Sex and lies are used to sell vapes online. Even we were surprised at the marketing tactics we found</a>
</strong>
</em>
</p>
<hr>
<h2>How about labelling?</h2>
<p>This leads to another reason why it’s impossible to tell what is in vapes – the lack of information, including warnings, <a href="https://www.legislation.gov.au/Details/F2021L00595">on the label</a>.</p>
<p>Even if labels are present, they don’t always reflect what’s in the product. Nicotine concentration of e-liquids is often quite different to what is on the label, and “nicotine-free” e-liquids often <a href="https://journal.chestnet.org/article/S0012-3692(20)30134-3/fulltext">contain nicotine</a>.</p>
<p>Products are also labelled with generic flavour names such as “berry” or “tobacco”. But there is no way for a user to know what chemicals have been added to make those “berry” or “tobacco” flavours or the changes in these chemicals that may occur with heating and/or interacting with other ingredients and the device components. “Berry” <a href="https://tobaccocontrol.bmj.com/content/30/2/185">flavour</a> alone could be made from <a href="https://tobaccocontrol.bmj.com/content/tobaccocontrol/suppl/2020/02/10/tobaccocontrol-2019-055447.DC1/tobaccocontrol-2019-055447supp001_data_supplement.pdf">more than 35</a> different chemicals. </p>
<p>Flavouring chemicals may be “food grade” or classified as safe-to-eat. However mixing them into e-liquids, heating and inhaling them is a very different type of exposure, compared to eating them.</p>
<p>One example is benzaldehyde (an almond flavouring). When this is inhaled, it <a href="https://pubs.acs.org/doi/abs/10.1021/acs.chemrestox.9b00171">impairs</a> the <a href="https://www.sciencedirect.com/science/article/pii/S2214750023000380">immune function</a> of lung cells. This could potentially reduce a vaper’s ability to deal with other inhaled toxins, or respiratory infections. </p>
<p>Benzaldehyde is one of only <a href="https://www.legislation.gov.au/Details/F2021L00595">eight</a> banned e-liquid ingredients in Australia. The list is so short because we don’t have enough information on the health effects if inhaled of other flavouring chemicals, and their interactions with other e-liquid ingredients.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1670806592961355777"}"></div></p>
<h2>Where to next?</h2>
<p>For us to better assess the health risks of vapes, we need to learn more about:</p>
<ul>
<li><p>what happens when flavour chemicals are heated and inhaled</p></li>
<li><p>the interactions between different e-liquid ingredients</p></li>
<li><p>what other contaminants may be present in e-liquids</p></li>
<li><p>new, potentially harmful, substances in e-cigarettes.</p></li>
</ul>
<p>Finally, we need to know more about how people use e-cigarettes so we can better understand and quantify the health risks in the real world.</p><img src="https://counter.theconversation.com/content/210462/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexander Larcombe has previously received funding for e-cigarette research from the National Health and Medical Research Council, Lung Foundation Australia, Minderoo Foundation, Health Department of Western Australia and Asthma Foundation of Western Australia. The funders played no role in the conduct of the research. He is also a member of the Australian Council on Smoking and Health (ACOSH).</span></em></p>It’s not just the ingredients we should be concerned about. The devices themselves release chemicals that end up in our blood and urine.Alexander Larcombe, Associate Professor and Head of Respiratory Environmental Health, Telethon Kids InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2093292023-07-10T20:09:55Z2023-07-10T20:09:55ZThe furry puss caterpillar’s venom packs a painful punch. Now new research shows it came from an unlikely source<figure><img src="https://images.theconversation.com/files/536469/original/file-20230710-25-6ofe7i.jpeg?ixlib=rb-1.1.0&rect=98%2C98%2C6491%2C4989&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Donald W. Hall</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Did you know venom – a toxic substance injected by one animal into another – has evolved around 100 times? </p>
<p>In our laboratory at the University of Queensland, my colleagues and I study all kinds of venomous animals. One reason we do this is to find new molecules that can be <a href="https://www.nature.com/articles/d42473-018-00315-6">used in medicines</a>, or as <a href="https://imb.uq.edu.au/article/2018/07/spider-venom-human-friendly-insecticides">bio-friendly insecticides</a>.</p>
<p>Scientists have used venom toxins from snakes, spiders and scorpions in various medical contexts, including to <a href="https://en.wikipedia.org/wiki/Captopril">lower blood pressure</a>, protect <a href="https://stories.uq.edu.au/imb/2020/venom/stroke/index.html">against stroke</a>, and <a href="https://en.wikipedia.org/wiki/Chlorotoxin">label tumours during surgery</a>.</p>
<p>There are several other groups of venomous animals, such as <a href="https://www.uq.edu.au/news/article/2018/02/assassin%E2%80%99s-venom-system-packs-deadly-double">assassin bugs</a> and <a href="https://www.mdpi.com/2072-6651/10/11/456">robber flies</a>, which have been largely neglected – yet their venom may prove to be just as useful to humans.</p>
<p>In research <a href="https://doi.org/10.1073/pnas.2305871120">published today</a> in the Proceedings of the National Academy of Sciences, our team investigated the venom from a group of caterpillars called asp caterpillars, which are notorious for their ability to cause excruciating pain. They’re also called puss caterpillars since they sport long, soft hairs that have been dubbed “toxic <a href="https://www.nationalgeographic.com/animals/article/toupee-caterpillar-venomous-animal-weird-insect">toupées</a>”.</p>
<p>We were surprised to find the main painful toxins in asp caterpillars belong to a family of molecules usually found in disease-causing bacteria. We discovered that a gene that codes for this kind of toxin hopped from bacteria to the ancestors of moths and butterflies millions of years ago, in a phenomenon called <a href="https://www.britannica.com/science/horizontal-gene-transfer">horizontal gene transfer</a>.</p>
<h2>Float like a butterfly, sting like a bee</h2>
<p>The insect group <a href="https://www.ento.csiro.au/education/insects/lepidoptera.html">Lepidoptera</a>, which we usually think of as butterflies and moths, are my favourite venomous animals. Interestingly, it’s always the larval forms (caterpillars) that are armed with venom, and not the adults. We think this is because caterpillars are particularly helpless against predators, and therefore need special defences. </p>
<p>This is also why venom has evolved multiple times just within Lepidoptera. Unlike most <a href="https://www.britannica.com/animal/arthropod">arthropods</a>, which use venom for hunting, caterpillars are among a select few (including bees) that use it purely to defend themselves from predators.</p>
<p>However, the venom of some of these caterpillar groups, including asp caterpillars, has never been examined with modern methods.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/536436/original/file-20230710-31-mrdrxy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/536436/original/file-20230710-31-mrdrxy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536436/original/file-20230710-31-mrdrxy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536436/original/file-20230710-31-mrdrxy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536436/original/file-20230710-31-mrdrxy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536436/original/file-20230710-31-mrdrxy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=530&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536436/original/file-20230710-31-mrdrxy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=530&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536436/original/file-20230710-31-mrdrxy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=530&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When touched, the tips of the smooth cylindrical venom spines break, injecting venom.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Evolution by horizontal gene transfer</h2>
<p>People who have been stung by asp caterpillars <a href="https://www.researchgate.net/figure/A-C-The-Asp-Caterpillar-Megalopyge-opercularis-can-vary-in-color-from-white-to-gray_fig1_5508450">have described</a> the feeling as being similar to “touching burning coals” or “being hit with a baseball bat”. We set out to find what this venom contains and how it can inflict such incredible pain.</p>
<p>Asp caterpillars aren’t found in Australia, so I had to travel to Florida to collect them from oak and elm trees. Although I couldn’t return with live individuals (due to the threat of invasive species), with the help of some US researchers I was able to bring some venom and preserved caterpillars back to the lab for analysis.</p>
<p>We used a variety of imaging and molecular techniques to build a picture of where the venom is made, what kinds of toxins it contains, and how those toxins produce pain. </p>
<p>Surprisingly, when we looked at the structures of the main pain-causing toxins, we found they belonged to a toxin group usually produced by bacteria, including disease-causing bacteria such as <em>E. coli</em> and salmonella. These caterpillar toxins work by punching holes in cells – the same mechanism the bacterial toxins use to inflict damage on humans. </p>
<p>When we analysed the family tree of the toxins in detail, we found a gene that codes for this kind of toxin had “hopped” from a bacterium to the ancestors of butterflies and moths hundreds of millions of years ago.</p>
<p>These hopping events are called horizontal gene transfer to distinguish them from the vertical transfer of genes from parents to offspring. These events are very rare. </p>
<p>In the case of asp caterpillars, DNA from the infecting bacteria would have not only had to come into contact with the ancestral caterpillar, but also get incorporated into its DNA, inside the cells that would become sperm or eggs (and be passed on to subsequent generations). </p>
<p>We know of only a few examples of the horizontal gene transfer of venom toxins.</p>
<h2>Harnessing nature’s resources</h2>
<p>Our study shows evolution and life are weirder and more complex than we usually assume. Beyond this, projects like this can also help us discover new ways in which venom toxins may benefit humans and the environment.</p>
<p>For example, toxins that make holes in cell membranes are already being investigated for their ability to <a href="https://www.nature.com/articles/s41467-019-13253-8">deliver lifesaving drugs</a> to the inside of cells.</p>
<p>Another potential application is in engineering toxins that could punch holes in cells to <a href="https://www.mdpi.com/2072-6651/15/4/297">selectively kill cancer cells</a>, while leaving normal cells intact. Our ability to develop such new technologies depends on discovering and understanding the molecular resources that exist in nature.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ever-wondered-whod-win-in-a-fight-between-a-scorpion-and-tarantula-a-venom-scientist-explains-155138">Ever wondered who'd win in a fight between a scorpion and tarantula? A venom scientist explains</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/209329/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This work was funded through the Australian Research Council through Discovery Project DP200102867.</span></em></p>This caterpillar can cause excruciating pain when touched. But unlike most venomous arthropods, it uses its venom purely for self-defence.Andrew Walker, Postdoctoral Research Fellow, Institute for Molecular Bioscience, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1983422023-06-20T09:33:09Z2023-06-20T09:33:09ZIs hot yoga good for you? Exploring the science behind the sweat<iframe id="noa-web-audio-player" style="border: none" src="https://embed-player.newsoveraudio.com/v4?key=x84olp&id=https://theconversation.com/is-hot-yoga-good-for-you-exploring-the-science-behind-the-sweat-198342&bgColor=F5F5F5&color=D8352A&playColor=D8352A" width="100%" height="110px"></iframe>
<p><a href="https://theconversation.com/yoga-isnt-timeless-its-changing-to-meet-contemporary-needs-97162">Hot yoga</a> also known as <a href="https://www.yoga-society.com/blogs/types-of-yoga/what-is-bikram-yoga">Bikram yoga</a> (more on that later) has <a href="https://www.cnet.com/health/fitness/benefits-of-hot-yoga/">gained significant popularity in recent years</a> as a fairly ferocious form of exercise. It combines yoga poses and breathing exercises and is practised in a heated studio – with room temperatures close to 40°C.</p>
<p>This style of yoga is designed to replicate the environmental conditions of India and is typically practised for around 90 minutes, leaving students (and teachers) dripping in sweat come the end of class.</p>
<p>Practising hot yoga challenges the mind and places additional physiological strain on the body. It makes you very sweaty and increases your heart rate, which can feel pretty intense. Indeed, hot yoga can lead to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5433110/">dehydration and dizziness</a>, especially if it’s your first time and you don’t begin the class hydrated.</p>
<p>Designed to develop strength, flexibility and balance, hot yoga is believed to offer enhanced physical and <a href="https://journals.copmadrid.org/pi/art/pi2022a4">mental health benefits</a> – including improved levels of fitness and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609431/">reduced stress levels</a>. </p>
<p>But it can also feel uncomfortable – think sweat trickling into your eyes while doing a headstand – and hard going: with fast, dynamic sequences repeated numerous times. Then there are also those tricky balances and multiple lunges, all done at high temperatures, meaning that at times classes can feel pretty gruelling.</p>
<p>So are all these hot sweaty postures actually any good for you? Let’s take a look at the science. </p>
<h2>The origins of hot yoga</h2>
<p>Before we go into the evidence, a bit on the history. Originally known as “<a href="https://www.shape.com/fitness/workouts/things-you-need-know-about-bikram-yoga">Bikram yoga</a>”, named after its creator Bikram Choudhury, the traditional style of hot yoga was developed in the early 1970s. It involves a series of 26 fixed postures, carried out over 90 minutes while experiencing extreme heat stress. </p>
<p>In recent years many yoga studios have chosen to <a href="https://www.theguardian.com/tv-and-radio/2019/dec/03/he-made-a-fortune-from-his-trademarked-bikram-yoga-but-now-his-empire-is-in-tatters">rebrand</a> these classes as “hot yoga”, having changed from the original 26 fixed postures to be more flowing and individual and to include music (which Bikram classes don’t). </p>
<p>Another reason many yoga studios have chosen to <a href="https://www.huffingtonpost.co.uk/entry/bikram-choudhury-sexual-assault_n_5d4dc527e4b0fd2733f0286f">move away from the Bikram style</a> of yoga is that <a href="https://www.theguardian.com/lifeandstyle/2017/feb/18/bikram-hot-yoga-scandal-choudhury-what-he-wanted">multiple women</a> have <a href="https://www.independent.co.uk/life-style/bikram-choudhury-yoga-rape-sexual-abuse-netflix-documentary-who-a9210771.html">come forward</a> with <a href="https://www.vogue.in/culture-and-living/content/bikram-hot-yoga-controversy-bikram-choudhury-sexual-assault-netflix-documentary">accusations of sexual harassment</a> and <a href="https://www.theguardian.com/film/2019/nov/20/bikram-choudhury-yoga-founder-abuse-netflix-documentary">assault against Choudhury</a>. This has led to <a href="https://www.latimes.com/local/lanow/la-me-ln-bikram-yoga-lawsuit-20160126-story.html">legal action</a> and been the focus of a 2019 Netflix documentary: <a href="https://www.netflix.com/gb/title/80221584">Bikram: Yogi, Guru, Predator</a>.</p>
<p>Even before the <a href="https://www.refinery29.com/en-gb/2019/11/8874728/bikram-yoga-founder-scandal-new-netflix-documentary">Bikram scandal</a>, not everyone in the yoga community backed the idea of hot yoga. This is because traditional yoga practice involves a series of postures known as sun salutations, which are performed early in the morning (when it’s cooler), not during the midday heat. </p>
<h2>What the science says</h2>
<p>Although <a href="https://hfjc.library.ubc.ca/index.php/HFJC/article/view/220">comprehensive scientific reviews</a> are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609431/">still lacking</a>, some studies have indicated potential health benefits from hot yoga. Modified Bikram yoga performed regularly has been <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609431/">associated with</a> increased aerobic fitness and improved cardiovascular function. </p>
<p>Hot yoga has <a href="https://journals.lww.com/nsca-jscr/Fulltext/2018/10000/Efficacy_of_Hot_Yoga_as_a_Heat_Stress_Technique.23.aspx">shown promise</a> in terms of <a href="https://www.liebertpub.com/doi/full/10.1089/acm.2012.0709">heart health</a>, by lowering “bad cholesterol” levels and <a href="https://pubmed.ncbi.nlm.nih.gov/24138995/">improving glucose tolerance</a>. Glucose intolerance may indicate an increased risk of metabolic conditions, such as diabetes.</p>
<p>It has <a href="https://journals.lww.com/nsca-jscr/fulltext/2013/03000/bikram_yoga_training_and_physical_fitness_in.35.aspx?casa_token=6VxlqbNhg6YAAAAA:Q1t8bes2-X1blvLrO0vMe7AdpxJyZ4xtU69WSWoLbTtwTb7kHur2Lv5XjeIsy7OIRntbCb5Le1ciqCsWq60MElzJaEqJWDQ">also been linked</a> to an increase in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609431/">strength</a>, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7241641/">flexibility</a> <a href="https://scielo.isciii.es/pdf/inter/v31n2/1132-0559-inter-31-2-0067.pdf">and enhanced mental health</a>, including improved stress management and sleep quality.</p>
<figure class="align-center ">
<img alt="Women in hot yoga studio sweating." src="https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Getting a sweat on for that mind-body connection.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fitness-asian-female-group-doing-namaste-527129368">Southtownboy Studio/Shutterstock</a></span>
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<p>Yoga is classified as a “light-intensity exercise” by the <a href="http://www.alternative-therapies.com/openaccess/ATHM_20_4_pate.pdf">American College of Sports Medicine</a> but <a href="https://www.researchgate.net/profile/Rajasree-Nambron-2/publication/281017791_Unilateral_spontaneous_adrenal_hemorrhage_in_pregnancy/links/55d14c3a08ae6a881385ec32/Unilateral-spontaneous-adrenal-hemorrhage-in-pregnancy.pdf#page=6">studies</a> show that hot yoga sessions can result in high heart rates, increased core temperatures of 38˚C-40˚C and substantial sweat losses – <a href="https://pubmed.ncbi.nlm.nih.gov/33230967/">up to 1.5 litres per session</a> – making it a more <a href="https://cdnsciencepub.com/doi/abs/10.1139/apnm-2017-0495">intense exercise</a>.</p>
<p>When it comes to hot yoga classes, <a href="https://www.lboro.ac.uk/microsites/lds/EEC/ICEE/textsearch/13proceedings/Environmental%20Ergonomics%20XV_Proceedings%20for%20Webpage_V1.pdf#page=153">research</a> has also found that novices and experienced practitioners exhibit similarities in heart rate but can differ in sweat rate and core temperature changes. The more experienced you are, the more you sweat and the hotter you may get. This is likely because more experienced hot yogis will be better adapted to the heat and so able to push harder.</p>
<p>It’s often claimed that practising yoga in a heated environment may help with “<a href="https://www.yogajournal.com/practice/does-yoga-detox-your-body/">detoxification</a>” and the release of <a href="https://www.cbsnews.com/news/reality-check-yoga-does-not-release-toxins-from-the-body/">toxins from the body</a> due to excessive sweating. But this is rubbish – that’s what our kidneys are for. The reality is that those who practice hot yoga will probably lose more <a href="https://physoc.onlinelibrary.wiley.com/doi/full/10.14814/phy2.14647#:%7E:text=Abstract,cation%20of%20the%20extracellular%20fluid.">sodium</a> (or salt) and so are more likely to become dehydrated through increased sweat loss compared to yoga in cooler conditions. </p>
<p>Given this, hot yoga may be of benefit to those wishing to adapt to heat stress. For example, athletes preparing for elite sports such as <a href="https://pubmed.ncbi.nlm.nih.gov/29979281/">hockey</a> – if performed safely. </p>
<h2>And the risks?</h2>
<p>Because hot yoga can be physically demanding, <a href="https://www.hindawi.com/journals/ecam/2015/428427/">it may not be suitable for everyone</a>, especially for those with certain medical conditions or sensitivity to heat. Plus, some of the research looking at the benefits of hot yoga <a href="https://pubmed.ncbi.nlm.nih.gov/22592178/">hasn’t been replicated</a> – essentially meaning that further investigations are required to fully understand the true value of hot yoga in terms of physical fitness.</p>
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<p>So while it does seem that there are some potential benefits, it’s important to be mindful of the potential risks associated with hot yoga, too. The heated environment, for example, can increase the risk of dehydration, heat exhaustion and potentially heat stroke, especially if <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5433110/">proper hydration practices</a> are not followed.</p>
<p>People with certain medical conditions, such as heart disease or high blood pressure, or those who are pregnant may need to exercise caution or consult their doctor before participating in hot yoga. And it’s vital that students listen to their bodies, take breaks when needed and stay hydrated throughout their practice.</p>
<p>With hot and humid conditions, on top of excessive sweating, hygiene and cleanliness is also important for you and your mat. So don’t forget your towel and wipe your mat down afterwards too.</p><img src="https://counter.theconversation.com/content/198342/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sweating it out can be beneficial for maintaining fitness and good mental health, but it’s not right for everyone.Ash Willmott, Senior Lecturer in Sport and Exercise Science, Anglia Ruskin UniversityJessica Mee, Senior Lecturer in Sport and Exercise Science, University of WorcesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2054562023-06-16T12:37:40Z2023-06-16T12:37:40ZCan we train our taste buds for health? A neuroscientist explains how genes and diet shape taste<figure><img src="https://images.theconversation.com/files/531177/original/file-20230609-22954-t3e9qh.jpg?ixlib=rb-1.1.0&rect=90%2C10%2C6619%2C4456&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers are increasingly learning that early diet can shape taste preferences but that our taste buds can also be trained to prefer healthier foods.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/young-female-nerd-holds-ice-cream-and-broccoli-royalty-free-image/679524590?phrase=vegetables+versus+sweets&adppopup=true">RichVintage/E+ via Getty Images</a></span></figcaption></figure><p>Have you ever wondered why only hummingbirds sip nectar from feeders?</p>
<p>Unlike sparrows, finches and most other birds, hummingbirds <a href="https://www.insidescience.org/video/why-hummingbirds-have-sweet-tooth">can taste sweetness</a> because they <a href="https://doi.org/10.1126/scisignal.2005818">carry the genetic instructions</a> necessary to detect sugar molecules.</p>
<p>Like hummingbirds, we humans can sense sugar because our DNA contains gene sequences coding for the <a href="https://theconversation.com/a-taste-for-sweet-an-anthropologist-explains-the-evolutionary-origins-of-why-youre-programmed-to-love-sugar-173197">molecular detectors</a> that allow us to detect sweetness. </p>
<p>But it is more complex than that. Our ability to sense sweetness, as well as other tastes, involves a delicate dance between our genetic makeup and the foods we encounter from the womb to the dinner table.</p>
<p>Neuroscientists <a href="https://scholar.google.com/citations?user=2LAmkegAAAAJ&hl=en">like me</a> are working to decipher how this <a href="https://doi.org/10.1007%2Fs11154-016-9360-5">intricate interplay between genes</a> <a href="https://doi.org/10.1016/j.tem.2020.11.011">and diet</a> shapes taste.</p>
<p>In <a href="https://sites.lsa.umich.edu/dus-lab/">my laboratory</a> at the University of Michigan, we are diving deeply into one specific aspect, which is how <a href="https://doi.org/10.1016/j.cub.2022.07.063">consuming too much sugar dulls the sense of sweetness</a>. Taste is so central to our eating habits that understanding how genes and the environment shape it has crucial implications <a href="http://health.euroafrica.org/books/dietnutritionwho.pdf">for nutrition</a>, <a href="https://www.who.int/publications/i/item/9789240039919">food science</a> and <a href="https://doi.org/10.1093/ajcn/nqaa302">disease prevention</a>.</p>
<h2>The role of genes in sensing taste</h2>
<p>As with hummingbirds, the <a href="https://www.webmd.com/diet/features/science-how-we-taste">human ability to discern what food tastes like</a> depends on the presence of taste receptors. These molecular detectors are found on the sensory cells, which are housed inside the taste buds, the sensory organs on the surface of the tongue. </p>
<p>The <a href="https://theconversation.com/a-taste-for-sweet-an-anthropologist-explains-the-evolutionary-origins-of-why-youre-programmed-to-love-sugar-173197">interactions between taste receptors and food molecules</a> give rise to the five basic taste qualities: sweetness, savoriness, bitterness, saltiness and sourness, which are transmitted from the mouth to the brain via specific nerves.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532282/original/file-20230615-17-tk80ew.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram of a taste bud, with arrows pointing to the taste pore, a taste receptor cell and taste cells." src="https://images.theconversation.com/files/532282/original/file-20230615-17-tk80ew.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532282/original/file-20230615-17-tk80ew.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=476&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532282/original/file-20230615-17-tk80ew.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=476&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532282/original/file-20230615-17-tk80ew.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=476&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532282/original/file-20230615-17-tk80ew.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532282/original/file-20230615-17-tk80ew.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532282/original/file-20230615-17-tk80ew.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A diagram of a taste bud, indicating different types of cells and the sensory nerve.</span>
<span class="attribution"><span class="source">Julia Kuhl and Monica Dus</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>For instance, when sugar binds to the sweet receptor, it signals sweetness. Our innate preference for the taste of some foods over others is rooted in how the tongue and the brain <a href="https://doi.org/10.1038/486S16a">became wired during our evolutionary history</a>. Taste qualities signaling the presence of essential nutrients and energy, like salt and sugar, send information to brain areas linked to pleasure. Conversely, tastes that alert us to potentially harmful substances, such as the bitterness of certain toxins, are connected to those that make us <a href="https://doi.org/10.1016/j.cub.2013.04.010">feel discomfort or pain</a>.</p>
<p>While the presence of genes encoding for functional taste receptors in our DNA allows us to <a href="https://doi.org/10.1038/486S16a">detect food molecules</a>, how we respond to these also depends on the unique combination of taste genes we carry. Like ice cream, genes, including those for taste receptors, come in different flavors. </p>
<p>Take, for instance, a taste receptor for bitterness called TAS2R38. Scientists <a href="https://doi.org/10.3389%2Ffgene.2019.01272">found small changes in the genetic code</a> for the TAS2R38 gene among different people. These genetic variants affect how people perceive the bitterness of vegetables, berries and wine. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/C4rdqXXzPGU?wmode=transparent&start=45" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Aside from allowing us to taste the wide variety of flavors in foods, taste also helps us distinguish between foods that are healthy or potentially harmful, such as spoiled milk.</span></figcaption>
</figure>
<p>Follow-up studies have suggested a link between those same variants and food choice, particularly with respect to <a href="https://www.reuters.com/article/us-alcohol-taste-genes/genes-influence-taste-and-possibly-use-of-alcohol-idINKCN0HL23U20140926">vegetable and alcohol consumption</a>. </p>
<p>Many more variants exist in our gene repertoire, including those for the sweet taste receptor. However, whether and how these genetic differences <a href="https://doi.org/10.1016/j.cofs.2021.07.001">affect our taste and eating habits</a> is still being worked out. What is certain is that while genetics lays the groundwork for taste sensations and preferences, experiences with food can profoundly reshape them. </p>
<h2>How diet influences taste</h2>
<p>Many of our innate sensations and preferences are molded by our <a href="https://www.npr.org/2011/08/08/139033757/babys-palate-and-food-memories-shaped-before-birth">early experiences with food</a>, sometimes before we’re even born. Some molecules from the mother’s diet, like garlic or carrots, reach the <a href="https://www.npr.org/2011/08/08/139033757/babys-palate-and-food-memories-shaped-before-birth">fetus’s developing taste buds via the amniotic fluid</a> and can affect the appreciation of these foods after birth.</p>
<p>Infant formula can also influence food preferences later on. For example, research shows that infants fed with formulas that are not based on cow’s milk – which are more bitter and sour because of their amino acid content – are more accepting of bitter, sour and savory foods such as vegetables after weaning than <a href="https://doi.org/10.3945/ajcn.2009.27462o">those who consume cow milk-based formula</a>. And <a href="https://theconversation.com/why-kids-shouldnt-eat-added-sugar-before-they-turn-2-according-to-a-nutritional-epidemiologist-173398">toddlers who drink sweetened water</a> strongly prefer <a href="https://doi.org/10.1007%2Fs11154-016-9360-5">sweet beverages as early as age 2</a>.</p>
<p>The effect of food on our taste predispositions doesn’t stop in early life: <a href="https://doi.org/10.1016/j.tem.2020.11.011">What we eat as adults</a>, especially our sugar and salt intake, can also shape how we perceive and potentially choose food. <a href="https://media.nutrition.org/wp-content/uploads/2020/01/NIH-Workshop-Slides-Beauchamp.pdf">Cutting down on sodium</a> in our diet decreases our preferred level of saltiness, whereas consuming more makes us like saltier foods.</p>
<p>Something similar occurs with sugar: <a href="https://doi.org/10.3945/ajcn.115.112300">Reduce sugar in your diet</a> and you may find food sweeter. Conversely, as <a href="https://doi.org/10.1016/j.cub.2022.07.063">research in rats</a> and <a href="https://doi.org/10.1016/j.celrep.2019.04.027">flies</a> suggests, high sugar levels may dull your sensation of sweetness.</p>
<p>Although we researchers are still working out the exact how and why, studies show that high sugar and fat intake in animal models <a href="https://doi.org/10.1016/j.tem.2020.11.011">dampens the responsiveness of taste cells</a> and <a href="https://doi.org/10.1016/j.cub.2022.07.063">nerves to sugars</a>, modifies the number of taste cells available and even flips <a href="https://theconversation.com/what-you-eat-can-reprogram-your-genes-an-expert-explains-the-emerging-science-of-nutrigenomics-165867">genetic switches</a> in the <a href="https://doi.org/10.7554/eLife.83979">taste cells’ DNA</a>.</p>
<p>In my lab, we’ve shown that these taste alterations in rats return to normal within weeks when the <a href="https://doi.org/10.1016/j.cub.2022.07.063">extra sugar is removed from the diet</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/531463/original/file-20230612-19-vqd4x5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Artistic image of a white lab rat standing on its high legs to sniff a chocolate dessert." src="https://images.theconversation.com/files/531463/original/file-20230612-19-vqd4x5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531463/original/file-20230612-19-vqd4x5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531463/original/file-20230612-19-vqd4x5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531463/original/file-20230612-19-vqd4x5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531463/original/file-20230612-19-vqd4x5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531463/original/file-20230612-19-vqd4x5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531463/original/file-20230612-19-vqd4x5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Animal studies have helped inform how high sugar intake affects taste and eating.</span>
<span class="attribution"><span class="source">Irina Ilina</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Illness can also influence taste</h2>
<p>Genetics and food aren’t the only factors that affect taste. </p>
<p>As many of us discovered <a href="https://theconversation.com/covid-19-smell-and-taste-how-is-covid-19-different-from-other-respiratory-diseases-139543">during the height of the COVID-19 pandemic</a>, <a href="https://doi.org/10.1038%2Fs41598-022-11864-8">disease can also play a role</a>. After testing positive for COVID-19, I couldn’t tell the difference between sweet, bitter and sour foods for months. </p>
<p>Researchers have found that about 40% of people infected with SARS-CoV-2 <a href="https://doi.org/10.1093/chemse/bjac001">experience impairment in taste and smell</a>. In about 5% of those people, these <a href="https://doi.org/10.1136/bmj-2021-069503">taste deficits persist</a> for months and years. </p>
<p>Although researchers don’t understand what causes these sensory alterations, the leading hypothesis is that the virus <a href="https://doi.org/10.1038/d41586-022-01627-w">infects the cells that support the taste and smell receptors</a>.</p>
<h2>Training taste buds for healthier eating</h2>
<p>By shaping our eating habits, the intricate dance between genes, diet, disease and taste can affect the risk for chronic diseases.</p>
<p>Beyond distinguishing food from toxins, the brain uses taste signals as a proxy to estimate the filling power of foods. In nature, the stronger a food tastes – in terms of sweetness or saltiness – is directly connected to its nutrient levels and calorie content. For example, a mango contains five times the amount of sugar than a cup of strawberries, and this is why it tastes sweeter and is more filling. Thus, taste is important not just for food enjoyment and choice, <a href="https://doi.org/10.1016%2Fj.physbeh.2021.113419">but also for regulating food intake</a>.</p>
<p>When taste is altered by diet or disease, <a href="https://doi.org/10.1016%2Fj.physbeh.2015.05.036">sensory and nutrient information could become “decoupled</a>” and no longer provide accurate information to our brains about portion size. Research shows this may also occur with <a href="https://www.washingtonpost.com/business/2020/03/10/common-artificial-sweetener-might-be-making-you-fatter-sicker-new-study-says/">consumption of</a> <a href="https://theconversation.com/whos-recommendation-against-the-use-of-artificial-sweeteners-for-weight-loss-leaves-many-questions-unanswered-206175">artificial sweeteners</a>.</p>
<p>And indeed, in recent studies in invertebrate animal models, our lab discovered that the changes in taste caused by <a href="https://doi.org/10.1016/j.celrep.2019.04.027">high dietary sugar intake</a> <a href="https://doi.org/10.7554/eLife.54530">drove higher eating</a> by <a href="https://doi.org/10.1016/j.cub.2022.11.039">impairing these food predictions</a>. Notably, many of the eating
patterns and brain changes we observed in flies have also been <a href="https://theconversation.com/diet-can-influence-mood-behavior-and-more-a-neuroscientist-explains-185360">discovered in</a> people who ate foods high in sugar or fat or who had high body-mass index. This raises the question of whether these effects also arise from taste and sensory alterations in our brains. </p>
<p>But there is a silver lining to the adaptable nature of taste. Since diet shapes our senses, we can actually train our taste buds – and our brains – to <a href="https://doi.org/10.1093/advances/nmaa151">respond and prefer foods with lower quantities of sugar</a> and <a href="https://www.ncbi.nlm.nih.gov/books/NBK50956/">salt</a>.</p>
<p>Interestingly, many people already say that they <a href="https://monell.org/big-data-says-food-is-too-sweet/">find foods overly sweet</a>, which may not be surprising since between 60% to 70% of <a href="https://www.nytimes.com/2016/05/22/upshot/it-isnt-easy-to-figure-out-which-foods-contain-sugar.html">grocery store foods contain added sugar</a>. Reformulating foods tailored to our genes and the plasticity of our taste buds could be a practical and powerful tool to <a href="https://www.who.int/publications/i/item/924120916X">enhance nutrition, promote health and decrease the burden of chronic disease</a>.</p><img src="https://counter.theconversation.com/content/205456/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Monica Dus is a tenured faculty at The University of Michigan College of Literature, Science, and the Arts in Ann Arbor, MI. She receives funding from the National Science Foundation, the National Institute of Health, the Sloan Foundation, the Rita Allen Foundation, and the Klingenstein Foundation; she is also a 2023 Guggenheim Fellow. Monica is the Junior Councilor for the Association for Chemoreception Sciences, on the Advisory Board for the Trends in Endocrinology & Metabolism journal, on the Editorial Board for the Chemical Senses journal, and the Natural Sciences representative to the University of Michigan Faculty Senate. </span></em></p>Research is clear that what we eat can drive our test preferences as early as 2 years of age.Monica Dus, Associate Professor of Molecular, Cellular, and Developmental Biology, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2034922023-05-03T12:07:00Z2023-05-03T12:07:00ZHeading to a beach this summer? Here’s how to keep harmful algae blooms from spoiling your trip<figure><img src="https://images.theconversation.com/files/523475/original/file-20230428-22-cp3c0a.jpg?ixlib=rb-1.1.0&rect=35%2C0%2C5862%2C3926&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Warning sign at Lido Key Beach in Sarasota, Fla., March 15, 2023, during a toxic algae bloom.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sign-warning-of-the-red-tide-risk-is-displayed-at-lido-key-news-photo/1248835855"> Jesus Olarte/AFP via Getty Images</a></span></figcaption></figure><p>Plunging into the ocean or a lake is one of the great joys of summer. But arriving at the beach to find water that’s green, red or brown, and possibly foul-smelling, can instantly spoil the party.</p>
<p>As a <a href="https://www.researchgate.net/profile/Brad-Reisfeld">toxicologist</a>, I study health risks from both synthetic and natural substances. I’ve conducted research into <a href="https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract_id/11137/report/0">early detection of harmful algal blooms</a>, or HABs, which are an increasing threat to humans, animals and the environment. </p>
<p>Toxins produced during these blooms have been implicated in human and animal illnesses in at least 43 states. Scientists have estimated that in the U.S. alone, freshwater HABs cause more than <a href="https://meetings.pices.int/publications/other/members/HAB-PolicyMakers.pdf">US$4.6 billion in damage yearly</a>. Here’s what to know about them if you’re bound for the water’s edge this summer.</p>
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<figcaption><span class="caption">Harmful algal blooms have become a regular occurrence along large stretches of Florida’s coast in recent years.</span></figcaption>
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<h2>Tiny organisms, big impacts</h2>
<p>Algae and cyanobacteria – often called blue-green algae – are simple, plantlike organisms that live in water. They can grow out of control, or “bloom,” especially when the water is warm and slow moving. Climate change is <a href="https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/">making water bodies warmer</a>, increasing the risk of HABs. </p>
<p>The other major factor that drives blooms is high levels of nutrients like nitrogen and phosphorus, which fertilize algae. <a href="https://www.epa.gov/sites/default/files/2015-03/documents/facts_about_nutrient_pollution_what_is_hypoxia.pdf">Nutrient pollution</a> comes mainly from agriculture, wastewater treatment plants, septic systems and fossil fuel combustion.</p>
<p>Sometimes these blooms contain organisms that produce toxins – an umbrella term for many poisonous substances that <a href="https://medlineplus.gov/ency/article/002331.htm">come from animals or plants</a> and can make people and animals sick and adversely affect the environment. These events are called harmful algal blooms. </p>
<p>HABs occur <a href="https://hab.whoi.edu/maps/regions-us-distribution/">throughout the U.S.</a> and <a href="https://hab.whoi.edu/maps/regions-world-distribution/">worldwide</a>, in both saltwater and freshwater environments. They pose significant health risks to human, pets, livestock and wildlife; damage ecosystems; increase water treatment costs; restrict recreational activities; and cut into economic revenues.</p>
<p>People and animals can be exposed to HAB toxins through many routes. These include skin contact during activities such as swimming or boating; inhaling airborne droplets that contain toxins; swallowing contaminated water; or eating food or supplements that contain toxins. The most severe effects generally result from <a href="https://hab.whoi.edu/impacts/impacts-human-health/">consuming contaminated seafood</a>.</p>
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<h2>An array of toxins</h2>
<p>There are numerous <a href="https://www.cdc.gov/habs/pdf/ohhabs-algae-algal-toxins-and-other-pathogens-lists.pdf">HAB toxins</a>, including substances such as microcystin, saxitoxin, cylindrospermopsin, anatoxin-A and domoic acid. Each has a different action on the body, so HABs can have <a href="https://mywaterquality.ca.gov/habs/resources/docs/humanhealth/hab_physician_guide_may2020.pdf">diverse harmful effects</a>.</p>
<p>Typical <a href="https://www.cdc.gov/habs/illness.html">symptoms of illness</a> from exposure to HAB toxins can include stomach pain, vomiting or diarrhea; headache, fever, tiredness or other general symptoms; skin, eye, nose or throat irritation; and neurological symptoms such as muscle weakness or dizziness. Depending on the toxin, higher levels of exposure can result in tremors or seizures, respiratory distress, kidney toxicity, liver toxicity and even death.</p>
<p>As with many environmental exposures, children and older people may be especially sensitive to HAB toxins. People who regularly consume seafood caught in HAB-prone areas are also at risk of long-term health effects from potentially frequent, low-level exposures to HAB toxins.</p>
<h2>Recognizing and responding to HABs</h2>
<p>It’s not possible to tell whether a bloom is harmful just by looking at it, but there are some warning signs. If the water appears green, red, brown or yellowish in color; has a strong musty or fishy odor; has foam, scum, algal mats or paintlike streaks on the surface; or if there are dead fish or other marine life in the water or washed up on the shoreline, it’s likely that a HAB may be occurring.</p>
<p>If you are unsure whether a bloom is harmful or not, contact your local health department or environmental agency for guidance. As a general rule, it’s good to check with local agencies to see whether there are any relevant warnings when you go to the beach. </p>
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<p>If you are notified of a bloom in a nearby body of water or in your public drinking water supply, the most important thing you can do to reduce your chances of getting sick is to follow local or state guidance. If you see signs of a bloom, stay out of the water and keep your pets out of the water.</p>
<p>It’s also important to follow local guidelines about consuming seafood caught through recreational fishing. It’s important to be aware that cooking contaminated seafood or boiling contaminated water <a href="https://www.webmd.com/food-recipes/food-poisoning/red-tide">does not destroy the toxins</a>. </p>
<h2>Be informed</h2>
<p>The U.S. Centers for Disease Control and Prevention provides <a href="https://www.cdc.gov/habs/general.html">resources and recommendations</a> related to HABs and ways to stay safe. Pet owners should also learn <a href="https://www.dec.ny.gov/docs/water_pdf/habspets.pdf">how to protect their dogs from HABs</a>. </p>
<p>Other federal agencies that offer information about HABs include <a href="https://hab.whoi.edu/">the U.S. National Office for Harmful Algal Blooms</a> and the <a href="https://www.niehs.nih.gov/health/topics/agents/algal-blooms/index.cfm">National Institute of Environmental Health Sciences</a>.</p>
<p>Many states conduct <a href="https://www.epa.gov/cyanohabs/state-habs-monitoring-programs-and-resources">HAB monitoring programs</a>, especially in areas that are known to be vulnerable to blooms, such as <a href="https://ohioseagrant.osu.edu/products/1h6jc/what-are-habs">western Lake Erie</a>. The U.S. Environmental Protection Agency offers <a href="https://www.epa.gov/cyanohabs/state-habs-resources">HAB resources by state</a>. Apps used by water quality managers and state officials who make management decisions about public water supply safety, including <a href="https://play.google.com/store/apps/details?id=com.topcoder.epa">CyAN Android</a> and <a href="https://qed.epa.gov/cyanweb/">CyANWeb</a>, may contain useful information about HABs in your area.</p>
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<h2>What’s being done about HABs?</h2>
<p>Many efforts are underway to prevent, control and mitigate HABs and provide early warnings to water system managers and health officials. </p>
<p>One example in the U.S. is the
<a href="https://www.epa.gov/water-research/cyanobacteria-assessment-network-cyan">Cyanobacteria Assessment Network, or CyAN</a>, a collaborative effort across several government agencies to develop an early warning indicator system to detect algal blooms in freshwater systems. There are also several ongoing projects for <a href="https://coastalscience.noaa.gov/science-areas/habs/hab-forecasts/">HAB forecasting by region</a>.</p>
<p>At the global scale, the <a href="https://data.hais.ioc-unesco.org/">Harmful Algal Information System</a> will eventually include harmful algal events and information from harmful algae monitoring and management systems worldwide.</p>
<p>Citizen scientists can provide invaluable help by monitoring local waters. If you would like to participate, consider joining the <a href="https://coastalscience.noaa.gov/monitoring-and-assessments/pmn/">Phytoplankton Monitoring Network</a> or <a href="https://cyanos.org/bloomwatch/">the Cyanobacteria Monitoring Collaborative</a>, and download and use the
<a href="https://cyanos.org/bloomwatch/">Cyanobacterial bloom app</a> to report potential HABs in bodies of water you visit.</p><img src="https://counter.theconversation.com/content/203492/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad Reisfeld received funding from the US Environmental Protection Agency to work on a project related to HABs detection</span></em></p>The tiny organisms that cause harmful blooms of algae can have a big impact on your trip to the shore. A toxicologist explains what causes these events and how to keep people and pets safe.Brad Reisfeld, Professor of Chemical and Biological Engineering, Biomedical Engineering, and Public Health, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1992512023-03-21T12:42:41Z2023-03-21T12:42:41ZPoisons are a potent tool for murder in fiction – a toxicologist explains how some dangerous chemicals kill<figure><img src="https://images.theconversation.com/files/515276/original/file-20230314-2595-90gnm9.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2121%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Poisons are often not so clearly labeled.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/poison-bottle-with-a-skull-royalty-free-image/1319519485">Josefe Photography/iStock via Getty Images Plus</a></span></figcaption></figure><p>People have used poisons <a href="https://accesspharmacy.mhmedical.com/content.aspx?bookid=2462&sectionid=194918294">throughout history</a> for a variety of purposes: to hunt animals for food, to <a href="https://theconversation.com/poison-or-cure-traditional-chinese-medicine-shows-that-context-can-make-all-the-difference-163337">treat diseases</a> and to achieve nefarious ends like murder and assassination.</p>
<p>But what is a poison? Do all poisons act in the same way? Does the amount of the poison matter in terms of its toxicity?</p>
<p><a href="https://www.engr.colostate.edu/cbe/people/brad-reisfeld/">I am a toxicologist</a> who studies how chemicals affect human health, particularly when they cause harmful effects. As a fan of mystery and detective stories, which often feature the use of poisons, I’ve noticed a few poisons that turn up repeatedly in books, television and movies. How they really work is as fascinating as how they’re deployed toward evil ends in fiction.</p>
<h2>What is a poison?</h2>
<p>The 16th-century <a href="https://pubmed.ncbi.nlm.nih.gov/27214290/">physician–alchemist Paracelsus</a>, considered to be the father of toxicology, once wrote: “What is there that is not poison? All things are poison and nothing is without poison. Solely the dose determines that a thing is not a poison.” By this adage, any substance can be a poison with the appropriate amount.</p>
<p>Many people intentionally expose themselves to chemicals like ethanol through alcoholic beverages, nicotine through tobacco products and botulinum toxin through botox treatments at relatively low doses and suffer minimal adverse effects. However, at <a href="https://accesspharmacy.mhmedical.com/content.aspx?bookid=2462&sectionid=194918464">sufficiently high doses</a>, these chemicals can be lethal. The body’s response often depends on how the chemical interacts with receptors within or on the surface of cells, or how it binds to enzymes used for biological processes. Frequently, higher concentrations of the substance <a href="https://doi.org/10.1016/j.tox.2013.04.007">lead to stronger responses</a>.</p>
<p>Despite Paracelsus’ dictum, in popular culture the term “poison” is often reserved for chemical compounds that are not normally encountered in daily life and can lead to detrimental health effects even in relatively small amounts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/515278/original/file-20230314-3245-vk99ad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Person dispensing white pills from a bottle into hand." src="https://images.theconversation.com/files/515278/original/file-20230314-3245-vk99ad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/515278/original/file-20230314-3245-vk99ad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515278/original/file-20230314-3245-vk99ad.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515278/original/file-20230314-3245-vk99ad.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515278/original/file-20230314-3245-vk99ad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515278/original/file-20230314-3245-vk99ad.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515278/original/file-20230314-3245-vk99ad.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">At a high enough dose, any chemical could be poisonous.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/young-man-spilling-multiple-pills-in-his-hand-royalty-free-image/1432823897">Malorny/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>Poisons in books, TV and film</h2>
<p>Novel writers and television and movie screenwriters have exploited numerous poisons in their works, including those that are chemical elements, such as <a href="https://web.archive.org/web/20090422045609/http://www.agathachristie.com/story-explorer/stories/450-from-paddington/">arsenic</a> and <a href="https://www.imdb.com/title/tt7737528/">polonium</a>, and those derived from animals, such as <a href="https://www.mrsherlockholmes.com/adventures/the-speckled-band/">snake venom</a> and <a href="https://columbophile.com/2019/11/24/episode-review-columbo-murder-under-glass/">blowfish poison</a>. Many poisons derived from plants have also been used for villainous purposes in fiction.</p>
<p>In the AMC TV series “<a href="https://www.imdb.com/title/tt0903747/">Breaking Bad</a>,” high school chemistry teacher Walter White uses a compound called ricin to murder the business executive Lydia Rodarte-Quayle. <a href="https://www.ncbi.nlm.nih.gov/books/NBK441948/">Ricin is a very potent poison</a> derived from the castor bean <em>Ricinus communis</em> and can be especially lethal if inhaled. Once this compound gets inside a cell, it <a href="https://doi.org/10.3390/ijms20051181">damages a structure called a ribosome</a> that’s responsible for synthesizing proteins essential to the cell’s function. Ingesting ricin could result in intestinal bleeding, organ damage and death.</p>
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<figcaption><span class="caption">It wasn’t Stevia that Lydia sweetened her tea with in ‘Breaking Bad’.</span></figcaption>
</figure>
<p>Sometimes, particular organs are much more susceptible to the effects of a poison. Physicians use <a href="https://cen.acs.org/articles/83/i25/Digoxin.html">digitalis medicines like digoxin</a>, which are derived from members of the foxglove family of plants, to treat congestive heart failure and heart rhythm problems. When administered in sufficiently high doses, however, they can lead to heart failure and death. By interfering with a protein in heart cells called the <a href="https://pubmed.ncbi.nlm.nih.gov/6328127/">sodium-potassium pump</a>, they can decrease the rate of electrical impulses in the heart and increase the strength of its contractions. This can result in a dangerous type of irregular heartbeat called ventricular fibrillation and lead to death.</p>
<p>The villain of the James Bond film “<a href="https://www.imdb.com/title/tt0381061/">Casino Royale</a>,” Le Chiffre, has his girlfriend attempt to kill Bond by poisoning his martini with digitalis. At high doses, digitalis drugs can alter the activity of the autonomic nervous system, which controls unconscious bodily functions like heart pumping. </p>
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<figcaption><span class="caption">Poison is one way to win a poker game.</span></figcaption>
</figure>
<p>TV characters are not immune to the dangers of poisonous mushrooms. One particularly potent fungus, <em>Amanita verna</em>, is known as the “destroying angel.” In the ITV TV series “<a href="https://www.imdb.com/title/tt0118401/?ref_=nv_sr_srsg_0">Midsomer Murders</a>,” puppet show owner and presumed upstanding citizen Evelyn Pope uses this mushroom to fatally poison chef Tristan Goodfellow as part of her murder spree of the inheritors of an estate. This mushroom contains <a href="https://doi.org/10.1016/j.wem.2017.10.002">various chemicals called amatoxins</a> that are thought to inhibit the activity of a specific enzyme critical for the production of <a href="https://www.genome.gov/genetics-glossary/messenger-rna">messenger RNA</a>, or mRNA, a molecule essential to protein synthesis in cells. Because ingested amatoxins mainly target the liver, these poisons can severely disrupt the <a href="https://theconversation.com/helping-the-liver-regenerate-itself-could-give-patients-with-end-stage-liver-disease-a-treatment-option-besides-waiting-for-a-transplant-191826">liver’s ability to repair itself</a>, leading to loss of function that will prove fatal without liver transplantation.</p>
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<figcaption><span class="caption">They don’t call it the “destroying angel” for nothing.</span></figcaption>
</figure>
<p>Another highly popular poison in detective and mystery stories is <a href="https://emergency.cdc.gov/agent/strychnine/basics/facts.asp">strychnine</a>. In the Agatha Christie story “<a href="https://www.agathachristie.com/stories/the-mysterious-affair-at-styles">The Mysterious Affair at Styles</a>,” Alfred Inglethorp and his lover Evelyn Howard use this poison to kill Inglethorp’s wife and wealthy country manor owner, Emily Inglethorp.</p>
<p>Strychnine, which comes from seeds of the <em>Strychnos nux-vomica</em> tree, <a href="https://doi.org/10.1039/d1np00079a">affects the nervous system</a> by blocking a neurotransmitter called glycine in the spinal cord and brainstem. Normally, glycine slows down the activity of neurons and prevents muscle contractions. By blocking glycine, strychnine ingestion can result in excessive activation of neurons and muscles, leading to a series of full-body muscle spasms that can become so intense that they cause respiratory arrest and death.</p>
<p>Many more poisons exist in nature than described here. Aside from potentially enhancing the enjoyment of detective and mystery stories, understanding the mechanisms of how these poisons work can provide an added appreciation for the complexity of the effects foreign chemicals have on the human body.</p><img src="https://counter.theconversation.com/content/199251/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad Reisfeld does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>From ‘Breaking Bad’ to James Bond, certain chemicals are popular options for characters looking to achieve nefarious ends.Brad Reisfeld, Professor of Chemical and Biological Engineering, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1986042023-02-08T18:39:30Z2023-02-08T18:39:30ZThe pollutants in our diet that could accelerate ageing<figure><img src="https://images.theconversation.com/files/506650/original/file-20230126-27856-g3ffre.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C5452%2C3400&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/es/image-illustration/concept-pollution-toxic-pollutants-inside-human-1332394850">Shutterstock / Lightspring</a></span></figcaption></figure><p>Pollutants are, by definition, harmful. But not all of them are equally harmful. Of the multitude of synthetic chemical compounds that pollute our environment, those that set off the loudest alarm bells are persistent organic pollutants (<a href="https://ec.europa.eu/environment/chemicals/international_conventions/index_en.htm">POPs</a>).</p>
<p>These are toxic compounds present in the environment, in water and in food. As their name suggests, their resistance to degradation makes them remain in the environment for a long time. To make matters worse, we are talking about easily diffusible compounds that accumulate in the adipose tissue of living beings and which are capable of damaging our health and the wider ecosystem. In short, they tick all the boxes in terms of causing us major problems.</p>
<p>To the list of problems we must add that, due to their free circulation around the globe through the atmosphere, POPs do not remain stagnant where they have been dumped. Quite the contrary: <a href="https://link.springer.com/article/10.1007/s00244-002-0131-9">they are</a> <a href="https://pubmed.ncbi.nlm.nih.gov/27146145/">present</a> <a href="https://pubs.acs.org/doi/abs/10.1021/es801004p">all over</a> <a href="https://pubs.acs.org/doi/10.1021/es0002464">the planet</a>.</p>
<p>PCBs have a molecular structure based on carbon and chlorine. This carbon-chlorine bond is difficult to break. Therefore, PCBs have a high permanence in the environment and are resistant to degradation.</p>
<p>Furthermore, they are semi-volatile despite their low vapour pressure because they have the ability to repel water from their surface. That is, PCBs with less chlorine in their structure are more volatile and more persistent, and can be transported over long distances. Moreover, by repelling water, they can bind to the lipids of living organisms and accumulate in their tissues. </p>
<p>The also have a great capacity for biomagnification – meaning they can accumulate to reach high levels of concentration the higher up the food chain they travel. That is why it is not uncommon for POPs to end up on our plates.</p>
<h2>Dioxins and PCBs</h2>
<p>There are many different types of POP. At the University of Navarre, we have focused on studying polychlorinated biphenyls (<a href="https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NHEERL&dirEntryId=341408">PCBs</a>) and dioxins (both omnipresent in the food chain) and particularly their presence in meat and dairy products, as well as fish and shellfish. Since certain PCBs and dioxins have similar mechanisms, it’s common that <a href="https://pubmed.ncbi.nlm.nih.gov/32625737/">they are studied together in the context of public health</a>.</p>
<p>PCBs are toxic chlorinated aromatic compounds whose formula was first described by Schmidt and Schultz in 1881. They are hydrophobic compounds, which gives them the ability to react with the lipids of living organisms and, therefore, to accumulate in their tissues.</p>
<p>PCBs were used as industrial fluids, including dielectric coolants in capacitors and transformers, until <a href="https://www.efsa.europa.eu/en/topics/topic/dioxins-and-pcbs">they were banned in most countries in the 1980s</a>. </p>
<p>On another note, the name “dioxins” normally groups together compounds belonging to two very different chemical structures: polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). </p>
<h2>Cardiovascular disease and cellular ageing</h2>
<p>More than 90% of human exposure to dioxins <a href="https://pubmed.ncbi.nlm.nih.gov/10912239/">occurs through food</a>, particularly meat and dairy products, as well as fish and shellfish. It is common to find PCBs in milk and its derivatives, but also in animal organs such as the brain and liver.</p>
<p>Dietary exposure to persistent organic pollutants has been associated with cardiovascular risk factors in humans. Within the <a href="https://www.unav.edu/web/departamento-de-medicina-preventiva-y-salud-publica/proyecto-sun">group of people analysed in the University of Navarre SUN Project</a> (“Seguimiento Universidad de Navarra” – “University of Navarre Monitoring”), several studies showed that PCB levels obtained from dietary intake were associated with a higher risk of developing hypertension and obesity.</p>
<p>Likewise, other studies showed an association between dietary exposure to PCBs and <a href="https://pubmed.ncbi.nlm.nih.gov/31918334/">coronary atherosclerosis</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/30776745/">heart failure</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/24759782/">obesity</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/31029940/">type 2 diabetes</a>, and mortality from <a href="https://pubmed.ncbi.nlm.nih.gov/29712742/">cardiovascular diseases</a>, among others.</p>
<p>Recently, researchers from the University of Navarre and the Physiopathology of Obesity and Nutrition Networking Biomedical Research Centre (CIBEROBN) have verified that high exposure to persistent organic pollutants (PCBs) through diet could also accelerate cellular ageing. </p>
<p>The research, based on 886 volunteers over the age of 55, was published <a href="https://pubmed.ncbi.nlm.nih.gov/35057533/">in the journal Nutrients</a> and has shown that these pollutants lead to telomere shortening. These non-coding DNA regions are found at the ends of the chromosomes and their length, in addition to reflecting life expectancy, indicates overall state of health. They also indicate the risk of chronic diseases.</p>
<p>Although more longitudinal studies are currently needed to corroborate this finding, the research highlights the influence of lifestyle and, specifically, diet on the integrity of genetic material or DNA.</p><img src="https://counter.theconversation.com/content/198604/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Las personas firmantes no son asalariadas, ni consultoras, ni poseen acciones, ni reciben financiación de ninguna compañía u organización que pueda obtener beneficio de este artículo, y han declarado carecer de vínculos relevantes más allá del cargo académico citado anteriormente.</span></em></p>Milk and its derivatives, meat products (especially fat), fish and seafood may be contaminated with PCBs, toxic substances that have been proven to accelerate cellular ageing.Amelia Marti del Moral, Catedrática de Fisiología, Universidad de NavarraLucía Alonso-Pedrero, Investigadora en Farmacia, Universidad de NavarraLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1970122023-01-18T13:38:33Z2023-01-18T13:38:33ZKicking off the new year by cleansing your body with a detox diet? A dietitian unpacks the science behind these fads<figure><img src="https://images.theconversation.com/files/503325/original/file-20230105-12-sxz5c4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C7988%2C5329&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A healthy diet – with plenty of fruits, vegetables and whole grains – is one key to a healthy body.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/young-woman-making-healthy-smoothie-for-breakfast-royalty-free-image/1237890164?phrase=juicing&adppopup=true">Oscar Wong/Moment via Getty Images</a></span></figcaption></figure><p>Detox diets are often touted as a way to cleanse the body after the excess food and drinks that come with the holidays. These diets promise quick results and can particularly entice people around the new year, when there tends to be a renewed focus on health and lifestyle habits. </p>
<p>There are <a href="https://www.nccih.nih.gov/health/detoxes-and-cleanses-what-you-need-to-know">a few different types of detox diets</a>: fasting, juice cleanses, eating only certain foods, using dietary commercial detox supplements or “cleansing” the colon with enemas or laxatives. </p>
<p>Most of these diets have a few things in common: They are short-term and aim to eliminate allegedly toxic substances from the body. Typically, these diets include a period of fasting followed by an extremely restrictive diet for a number of days. </p>
<p><a href="https://www.linkedin.com/in/taylor-grasso-rdn-ld-mpp-d-214747a2/">As a registered dietitian</a>, I have seen clients attempt detox diets and experience a slew of negative side effects, including developing a negative relationship with food. </p>
<p>Research shows that there is little evidence to <a href="https://doi.org/10.1111/jhn.12286">support the use of detox diets</a> and that they are not needed anyway. The body is well-equipped to eliminate unwanted substances on its own, without expensive and potentially harmful supplements sold by the nutrition and wellness industry. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/DESCcjSQSKY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Doing a cleanse doesn’t “clean your pipes” – and it may do harm.</span></figcaption>
</figure>
<h2>About toxins</h2>
<p>What are toxins – and how do they get into the body in the first place? </p>
<p>Internal toxins <a href="https://en.wikipedia.org/wiki/Toxin">include natural byproducts</a> created by the body during metabolism, such as lactic acid, urea and waste from the gut microbes. </p>
<p><a href="https://www.atsdr.cdc.gov/csem/exposure-history/Organ-Systems-Are-Affected.html">External toxic exposures</a> enter the body through eating, drinking, breathing or penetration of the skin. These can come in the form of air pollutants, food or water contaminated with chemicals or heavy metals, household products such as laundry detergent and even beauty products like facial cleansers, body wash and makeup.</p>
<p>The body’s built-in detoxification system includes the liver and kidneys, with assistance from the lungs, lymphatic system, digestive tract and skin. Briefly, the liver breaks down harmful substances, which are then filtered out through the kidneys. The digestive tract also expels them through bowel movements. </p>
<p>But our bodies aren’t always functioning optimally. That’s why a proper diet and improved lifestyle behaviors, such as increased exercise and sleep, may have a significant – and positive – impact on the body’s detoxification system.</p>
<p>Having a diverse microbiome and an <a href="https://www.healthline.com/nutrition/improve-gut-bacteria#TOC_TITLE_HDR_11">abundance of healthy gut bacteria</a> also helps to rid the body of harmful substances. Fermented foods such as kefir, sauerkraut and cultured dairy products can benefit gut health. These foods contain <a href="https://www.healthline.com/nutrition/11-super-healthy-probiotic-foods">probiotics</a>, which are the beneficial bacteria that live in your gut. </p>
<p>Another category, called <a href="https://www.eatingwell.com/article/2059033/best-and-worst-foods-to-eat-for-gut-health/">prebiotic foods</a>, are also beneficial for gut health. They provide nutrition and energy for the healthy probiotics in the gut and are high in fiber. Examples of prebiotic foods are whole grains and fruits and vegetables, particularly bananas, greens, onions and garlic. </p>
<h2>The potential harms of detox diets</h2>
<p>Through glossy and pervasive advertising, detox diets perpetuate <a href="https://www.nccih.nih.gov/health/detoxes-and-cleanses-what-you-need-to-know">a quick-fix mindset about weight and body image</a> rather than promote lifestyle changes that are sustainable for a lifetime. </p>
<p>Although proponents claim that detox diets and juice cleanses lead to weight loss, improved liver function and overall better health, research shows <a href="https://doi.org/10.1111/jhn.12286">they have little to no effect</a>. What’s more, they can <a href="https://www.nutritionletter.tufts.edu/healthy-eating/weight-mgmt/detox-dilemma/">lead to side effects</a>, including headaches, fatigue, weakness, fainting and irritability. However, studies show there is some evidence that certain foods and spices, such as coriander, may <a href="https://doi.org/10.1111/jhn.12286">enhance the body’s natural detoxification pathways</a>.</p>
<p>According to the Academy of Nutrition and Dietetics, other foods that may give the body’s own detox system a boost include cruciferous vegetables like broccoli and Brussels sprouts, berries, artichokes, garlic, onions, leeks and green tea. Eating adequate amounts of lean protein may also benefit the body’s natural system by <a href="https://www.eatright.org/health/wellness/diet-trends/whats-the-deal-with-detox-diets#">maintaining adequate levels of glutathione</a>, the body’s master detoxification enzyme, or catalyst. Glutathione is an enzyme produced by the liver that is <a href="https://www.webmd.com/vitamins/ai/ingredientmono-717/glutathione">involved in numerous processes</a> within the body including building and repairing tissues, assisting in the natural detoxification process and improving immune system function.</p>
<p>A handful of clinical studies have shown increased liver detoxification with a commercial detox diet or supplements, but these studies have <a href="https://doi.org/10.1111/jhn.12286">flawed methodologies and small sample sizes and are often done on animals</a>. In addition, supplements are <a href="https://www.fda.gov/consumers/consumer-updates/it-really-fda-approved#">not regulated by the U.S. Food and Drug Administration</a> as food and drugs are. They can be put on the shelf without full evaluation of ingredients or proven efficacy, except in rare cases in which supplements are tested by a third party. </p>
<p>In fact, some commercial supplements have raised so many health and safety issues that the FDA and the Federal Trade Commission <a href="https://www.nccih.nih.gov/health/detoxes-and-cleanses-what-you-need-to-know">have taken legal action against the companies that make them</a> to remove their products from the market. </p>
<p>Some detox diets and programs can have serious side effects, particularly those including laxatives or enemas, or those that restrict intake of solid foods. These approaches can lead to <a href="https://www.nccih.nih.gov/health/detoxes-and-cleanses-what-you-need-to-know">dehydration, nutrient deficiencies and electrolyte imbalances</a>. </p>
<p>In addition, diets that severely restrict certain foods or food groups <a href="https://doi.org/10.1007/s11894-017-0603-8">usually don’t lead to lasting weight loss</a>.</p>
<p>Instead, these types of diets often put the body into “<a href="https://doi.org/10.1038/ijo.2010.184">starvation mode</a>.” That means that rather than burning calories, your body holds on to them to use as energy. </p>
<p>Doing that repeatedly over a long period can <a href="https://doi.org/10.1038/ijo.2010.184">lead to a chronic decrease in metabolism</a>, which means that the number of calories you burn at rest may slowly decrease over time. This can make it more difficult to lose weight and balance blood sugar. It can also leave people more susceptible to chronic metabolic conditions such as cardiovascular disease and diabetes. </p>
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<figcaption><span class="caption">There’s very little evidence that detox diets remove harmful substances from your body.</span></figcaption>
</figure>
<h2>A healthy lifestyle, without the detox diet</h2>
<p>Focusing on sustainable lifestyle shifts can make a huge difference – and unlike a detox diet, actually work. </p>
<p>Number one, <a href="https://www.hsph.harvard.edu/nutritionsource/healthy-eating-plate/">eat a balanced diet</a>. Aim to eat mostly whole grains, lean protein choices, fruits and vegetables of many colors, low-fat dairy, nuts and seeds. This way, you’re getting a variety of nutrients, antioxidants and a good amount of fiber. </p>
<p>Number two, <a href="https://www.eatright.org/health/essential-nutrients/water/how-much-water-do-you-need">hydrate</a>. For women, the <a href="https://www.eatright.org/health/essential-nutrients/water/how-much-water-do-you-need">recommended daily water intake by the Academy of Nutrition and Dietetics</a> is 11½ cups; for males, it’s 15½ cups. However, you get about 20% of that total from food, which leaves nine cups for women and 13 cups for men as the daily recommended water intake. This is comparable to 4½ 16-ounce water bottles for women and 6½ 16-ounce water bottles for men. </p>
<p>Lastly, move your body in a way that you enjoy. The more you enjoy being active, the more likely it will become a routine. Aim for at least 150 minutes, or 2½ hours of <a href="https://www.cdc.gov/physicalactivity/basics/adults/index.htm#:%7E">moderate-intensity physical activity every week</a>. </p>
<p>Focusing on these types of long-term, sustainable healthy habits is the key to weight loss and overall health and wellness.</p><img src="https://counter.theconversation.com/content/197012/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Taylor Grasso consults for Simply Healthy, LLC and CU Anschutz Health and Wellness Center. </span></em></p>Detox diets and cleanses supposedly clear the body of allegedly toxic substances. But the evidence suggests otherwise.Taylor Grasso, Registered Dietitian, University of Colorado Anschutz Medical CampusLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1751942022-02-06T14:51:33Z2022-02-06T14:51:33ZAre mosquito-killing natural pesticides unintentionally harming frogs?<figure><img src="https://images.theconversation.com/files/443558/original/file-20220131-118399-gsobvc.jpg?ixlib=rb-1.1.0&rect=50%2C50%2C3664%2C2036&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mosquito eggs float on the surface of a pond. The insecticide Bti is used to kill mosquito larvae, but it could also harm frogs.
</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>The question of how pesticides affect public health and the environment has generated a lot of attention <a href="http://www.assnat.qc.ca/en/travaux-parlementaires/commissions/capern/mandats/Mandat-40773/index.html">in Québec</a>. Pesticides are widely used and often end up in our natural environment.</p>
<p>Pesticides are useful for killing weeds (herbicides), fungi (fungicides), insect pests in agriculture and fleas in pets (insecticides). They are also used to reduce the numbers of biting insects in urban and rural environments.</p>
<p>We have recently studied the indirect health effects on frogs of a biopesticide that has been in use for several decades, mainly to reduce the number of bothersome mosquitoes.</p>
<h2>Bacterial proteins are naturally occurring insecticides</h2>
<p><a href="https://www.canada.ca/en/health-canada/services/consumer-product-safety/reports-publications/pesticides-pest-management/fact-sheets-other-resources/bacillus-thuringiensis-subspecies-israelensis.html">Bti is one of a number of pesticides used worldwide</a> to reduce the populations of biting insects that breed in wetlands. This biological insecticide is composed of natural toxins from the bacterium <em>Bacillus thuringiensis israelensis</em>.</p>
<p>These toxins, synthesized in the form of crystals, belong to the Cry family of proteins, and target the larvae of biting insects such as mosquitos and blackflies. After the larvae ingests the crystals, they dissolve in the digestive tract and are transformed into toxic proteins that destroy the walls of the intestine, killing the larvae.</p>
<p>In principle, Cry toxins should not affect the intestinal walls of vertebrate species (mammals, birds, reptiles, amphibians and fish) because the digestive conditions of these species do not favour the transformation of the crystals into destructive proteins. According to <a href="https://www.canada.ca/en/health-canada/services/consumer-product-safety/reports-publications/pesticides-pest-management/fact-sheets-other-resources/bacillus-thuringiensis-subspecies-israelensis.html">Health Canada</a> Bti is not a high risk to other animals and humans.</p>
<p>However, the use of Bti <a href="https://environmentalevidencejournal.biomedcentral.com/articles/10.1186/s13750-019-0175-1">remains controversial</a>.</p>
<h2>Toxic effects or no effects of Bti formulations?</h2>
<p>Bti is often applied directly to small bodies of water, such as marshes, to specifically target aquatic mosquito and blackfly larvae. It could potentially impact other aquatic animal species, such as frog tadpoles, which are known to be sensitive to pollutants.</p>
<p>Some studies have shown that Bti formulations can be directly toxic to frogs, while others have revealed no effects.</p>
<p>For example, two Argentinian studies reported that a commercial formulation of Bti, called Introban, was toxic to tadpoles of the Creole frog. However, <a href="https://pubs.acs.org/doi/10.1021/acs.est.1c02322">our work</a> showed that a Bti formulation called VectoBac did not cause mortality in wood frog and American toad tadpoles.</p>
<figure class="align-center ">
<img alt="Experimental laboratory with aquaria" src="https://images.theconversation.com/files/443565/original/file-20220131-139881-e0m14f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443565/original/file-20220131-139881-e0m14f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443565/original/file-20220131-139881-e0m14f.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443565/original/file-20220131-139881-e0m14f.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443565/original/file-20220131-139881-e0m14f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443565/original/file-20220131-139881-e0m14f.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443565/original/file-20220131-139881-e0m14f.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Valerie Langlois and her team are studying the effects of some commercial Bti formulations on frogs.</span>
<span class="attribution"><span class="source">(Valerie Langlois)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>These contrasting results could be attributed to the different Bti formulations used in one country or another, the product’s potency, the species used or the environmental conditions during the experiments. Each commercial Bti product also contains additives that are known only to their manufacturers and whose effects on tadpoles are not known.</p>
<p>Our team has written about these differences in an article published in the scientific journal <a href="https://pubmed.ncbi.nlm.nih.gov/33876257/"><em>Archives of Environmental Contamination and Toxicology</em></a>.</p>
<h2>Metamorphosis and intestinal microbiota</h2>
<p>The results of our study, published recently in the journal <a href="https://pubs.acs.org/doi/10.1021/acs.est.1c02322"><em>Environmental Science & Technology</em></a>, revealed that VectoBac may affect frog metamorphosis — the transition from tadpole to young frog.</p>
<p>In wood frogs and American toads, two types of VectoBac altered the time it took a tadpole to metamorphose, either delaying metamorphosis by nearly five days or advancing it by one day, depending on the treatment. Studies on frog ecology have established that early metamorphosis reduces a frog’s chance of survival, which could ultimately reduce population sizes. </p>
<p>In addition to metamorphosis, both types of VectoBac we studied altered the composition of the gut bacterial community of exposed young toads. Indeed, with the application rates recommended by the manufacturer, there was an increase in the relative abundance of certain families of gut bacteria. The impact of these changes remains unknown.</p>
<p>A <a href="https://doi.org/10.1038/s41467-017-00119-0">2017 study</a> by Jason Rohr of the University of Pittsburgh showed that disruption of the microbiota of amphibians decreases resistance to parasites later in life. Our team will focus on determining whether Bti-induced changes in microbiota impact the physiology of frogs in the long-term.</p>
<h2>The precautionary principle</h2>
<p>Should the <a href="https://www.europarl.europa.eu/RegData/etudes/IDAN/2015/573876/EPRS_IDA(2015)573876_EN.pdf">precautionary principle</a>, which states that “a substance should be considered potentially harmful to human health and the environment until proven otherwise,” be applied to amphibian habitats?</p>
<p>Our results indicate that the impact of commercial Bti products on amphibian health is variable among the species we studied, but our understanding remains limited. Bti formulations contain ingredients other than just natural toxins and we do not yet know if these have any effects on tadpoles.</p>
<p>As a result, we recommend that the application of Bti products in amphibian-rich ecosystems be targeted and minimized, taking into account sensitive periods during a frog’s life cycle, including reproduction and development of eggs into young frogs.</p>
<p>These precautions should be applied until research is conducted to assess whether the observed changes in metamorphosis and gut microbiota have adverse effects on amphibian populations.</p><img src="https://counter.theconversation.com/content/175194/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Valérie S. Langlois has received funding from the Quebec's Ministère des Forêts, de la Faune et des Parcs du Québec (MFFP) and holds the Canada Research Chair (CRC) in Ecotoxicogenomics and Endocrine Disruption.</span></em></p><p class="fine-print"><em><span>Juan Manuel Gutierrez-Villagomez has received funding from the Ministère des Forêts, de la Faune et des Parcs du Québec (MFFP). </span></em></p><p class="fine-print"><em><span>Madelaine Empey is a PhD student of Dr. Vance Trudeau's and receives funding from his laboratory and from the City of Ottawa.</span></em></p><p class="fine-print"><em><span>Vance L Trudeau has received funding from the City of Ottawa, G.D.G. Environment Ltd., NSERC and a University Research Chair in Neuroendocrinology at the University of Ottawa.</span></em></p>The insecticide Bti kills target organisms like mosquitoes and blackflies, but new research shows it may also have negative effects on non-target species like frogs.Valérie S. Langlois, Professor/Professeure titulaire, Institut national de la recherche scientifique (INRS)Juan Manuel Gutierrez-Villagomez, Postdoctoral research fellow, Institut national de la recherche scientifique (INRS)Madelaine Empey, PhD Student, Biology, L’Université d’Ottawa/University of OttawaVance L Trudeau, Professor, Department of Biology, L’Université d’Ottawa/University of OttawaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1733952021-12-08T23:51:24Z2021-12-08T23:51:24ZA century of tragedy: How the car and gas industry knew about the health risks of leaded fuel but sold it for 100 years anyway<figure><img src="https://images.theconversation.com/files/436454/original/file-20211208-104971-1bl6u5i.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5227%2C3413&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">For decades, most gas sold in the U.S. contained a lead additive.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/rusty-petrol-pumps-on-a-gas-station-royalty-free-image/74166712?adppopup=true"> Per Magnus Persson via Getty Images</a></span></figcaption></figure><p>On the frosty morning of Dec. 9, 1921, in Dayton, Ohio, researchers at a General Motors lab poured a new fuel blend into one of their test engines. Immediately, the engine began running more quietly and putting out more power. </p>
<p>The new fuel was tetraethyl lead. With vast profits in sight – and very few public health regulations at the time – General Motors Co. rushed gasoline diluted with tetraethyl lead to market despite the known health risks of lead. They named it “Ethyl” gas.</p>
<p>It has been 100 years since that pivotal day in the development of leaded gasoline. As a <a href="https://scholar.google.com/citations?view_op=search_authors&mauthors=bill+kovarik&hl=en&oi=ao">historian of media and the environment</a>, I see this anniversary as a time to reflect on the role of public health advocates and environmental journalists in preventing profit-driven tragedy.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/436459/original/file-20211208-17-xev9b9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white photo of a man in an old laboratory." src="https://images.theconversation.com/files/436459/original/file-20211208-17-xev9b9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436459/original/file-20211208-17-xev9b9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=353&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436459/original/file-20211208-17-xev9b9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=353&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436459/original/file-20211208-17-xev9b9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=353&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436459/original/file-20211208-17-xev9b9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=444&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436459/original/file-20211208-17-xev9b9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=444&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436459/original/file-20211208-17-xev9b9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=444&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Scientists working for General Motors discovered that tetraethyl lead could greatly improve the efficiency and longevity of engines in the 1920s.</span>
<span class="attribution"><span class="source">Courtesy of General Motors Institute</span></span>
</figcaption>
</figure>
<h2>Lead and death</h2>
<p>By the early 1920s, <a href="https://www.biologicaldiversity.org/campaigns/get_the_lead_out/pdfs/health/Needleman_1999.pdf">the hazards of lead were well known</a> – even Charles Dickens and Benjamin Franklin had written about the dangers of lead poisoning.</p>
<p>When GM began selling leaded gasoline, public health experts <a href="https://doi.org/10.1021/om030621b">questioned its decision</a>. One called lead a serious menace to public health, and another called concentrated tetraethyl lead a “<a href="https://doi.org/10.1021/om030245v">malicious and creeping</a>” poison. </p>
<p>General Motors and Standard Oil waved the warnings aside until disaster struck in October 1924. Two dozen workers at a refinery in Bayway, New Jersey, came down with severe lead poisoning from a poorly designed GM process. At first they became disoriented, then burst into insane fury and collapsed into hysterical laughter. Many had to be wrestled into straitjackets. <a href="https://www.nytimes.com/1924/10/27/archives/odd-gas-kills-one-makes-four-insane-stricken-at-work-in-standards.html">Six died, and the rest were hospitalized</a>. Around the same time, 11 more workers died and several dozen more were disabled at similar GM and DuPont plants across the U.S.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/436460/original/file-20211208-149721-820cnb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A cartoon showing a man going insane after lead exposure." src="https://images.theconversation.com/files/436460/original/file-20211208-149721-820cnb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436460/original/file-20211208-149721-820cnb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=183&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436460/original/file-20211208-149721-820cnb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=183&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436460/original/file-20211208-149721-820cnb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=183&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436460/original/file-20211208-149721-820cnb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=230&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436460/original/file-20211208-149721-820cnb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=230&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436460/original/file-20211208-149721-820cnb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=230&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The news media began to criticize Standard Oil and raise concerns over Ethyl gas with articles and cartoons.</span>
<span class="attribution"><span class="source">New York Evening Journal via The Library of Congress</span></span>
</figcaption>
</figure>
<h2>Fighting the media</h2>
<p>The auto and gas industries’ attitude toward the media was hostile from the beginning. At Standard Oil’s first press conference about the 1924 Ethyl disaster, a spokesman claimed he had no idea what had happened while advising the media that “<a href="https://www.nytimes.com/1924/10/27/archives/odd-gas-kills-one-makes-four-insane-stricken-at-work-in-standards.html">Nothing ought to be said about this matter in the public interest</a>.”</p>
<p><a href="https://billkovarik.com/wp-content/uploads/2012/08/Ethyl.Controversy.Kovarik.dissertation.pdf">More facts emerged in the months after the event</a>, and by the spring of 1925, in-depth newspaper coverage started to appear, framing the issue as public health versus industrial progress. A New York World article asked Yale University gas warfare expert Yandell Henderson and GM’s tetraethyl lead researcher Thomas Midgley whether leaded gasoline would poison people. Midgley joked about public health concerns and falsely insisted that leaded gasoline was the only way to raise fuel power. To demonstrate the negative impacts of leaded fuel, Henderson estimated that 30 tons of lead would fall in a dusty rain on New York’s Fifth Avenue every year. </p>
<p>Industry officials were outraged over the coverage. A GM public relations history from 1948 called the New York World’s coverage “a campaign of publicity against the public sale of gasoline containing the company’s antiknock compound.” GM also claimed that the media labeled leaded gas “loony gas” when, in fact, it was <a href="https://billkovarik.com/wp-content/uploads/2012/08/Ethyl.Controversy.Kovarik.dissertation.pdf">the workers themselves who named it as such</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/436735/original/file-20211209-141178-1klcf7s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An old advertisement for Ethyl brand gas." src="https://images.theconversation.com/files/436735/original/file-20211209-141178-1klcf7s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436735/original/file-20211209-141178-1klcf7s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436735/original/file-20211209-141178-1klcf7s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436735/original/file-20211209-141178-1klcf7s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436735/original/file-20211209-141178-1klcf7s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436735/original/file-20211209-141178-1klcf7s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436735/original/file-20211209-141178-1klcf7s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leaded gas was marketed as Ethyl, a joint brand of Standard Oil and General Motors.</span>
<span class="attribution"><a class="source" href="http://hdl.loc.gov/loc.pnp/mrg.05719">John Margolies/Library of Congress</a></span>
</figcaption>
</figure>
<h2>Attempts at regulation</h2>
<p>In May 1925, the U.S. Public Health Service asked GM, Standard Oil and public health scientists to attend an open hearing on leaded gasoline in Washington. The issue, according to GM and Standard, involved refinery safety, not public health. Frank Howard of Standard Oil argued that tetraethyl lead was diluted at over 1,000 to 1 in gasoline and therefore posed no risk to the average person. </p>
<p>Public health scientists <a href="https://billkovarik.com/wp-content/uploads/2012/08/Ethyl.Controversy.Kovarik.dissertation.pdf">challenged the need for leaded gasoline</a>. Alice Hamilton, a physician at Harvard, said, “There are thousands of things better than lead to put in gasoline.” And she was right. There were plenty of well-known alternatives at the time, and some were even patented by GM. But no one in the press knew how to find that information, and the Public Health Service, under pressure from the auto and oil industries, canceled a second day of public hearings that would have discussed safer gasoline additives like ethanol, iron carbonyl and catalytic reforming. </p>
<p>By 1926, the Public Health Service announced that they had “no good reason” to prohibit leaded gasoline, even though <a href="https://billkovarik.com/wp-content/uploads/2012/08/Ethyl.Controversy.Kovarik.dissertation.pdf">internal memos complained that their research</a> was “half baked.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/436456/original/file-20211208-68670-1nmlwhl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graph showing that blood lead levels closely follow lead emissions from cars." src="https://images.theconversation.com/files/436456/original/file-20211208-68670-1nmlwhl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436456/original/file-20211208-68670-1nmlwhl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436456/original/file-20211208-68670-1nmlwhl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436456/original/file-20211208-68670-1nmlwhl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436456/original/file-20211208-68670-1nmlwhl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=508&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436456/original/file-20211208-68670-1nmlwhl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=508&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436456/original/file-20211208-68670-1nmlwhl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=508&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">As leaded gasoline fell out of use, lead levels in people’s blood fell as well.</span>
<span class="attribution"><a class="source" href="https://www.epa.gov/lead">U.S. EPA</a></span>
</figcaption>
</figure>
<h2>The rise and fall of leaded gasoline</h2>
<p>Leaded gasoline went on to dominate fuel markets worldwide. Researchers have estimated that decades of burning leaded gasoline caused <a href="https://news.un.org/en/story/2011/10/393292-phase-out-leaded-petrol-brings-huge-health-and-cost-benefits-un-backed-study">millions of premature deaths, enormous declines in IQ levels</a> and many other associated social problems.</p>
<p>In the 1960s and 1970s, the public health case against leaded gasoline reemerged. A California Institute of Technology geochemist, Clair Cameron Patterson, was finding it difficult to measure lead isotopes in his laboratory because lead from gasoline was everywhere and his samples were constantly being contaminated. Patterson created the first “clean room” to carry on his isotope work, but he also published a 1965 paper, “<a href="https://doi.org/10.1080/00039896.1965.10664229">Contaminated and Natural Lead Environments of Man</a>,” and said that “the average resident of the U.S. is being subjected to severe chronic lead insult.”</p>
<p>In parallel, by the 1970s, the U.S. Environmental Protection Agency decided that leaded gasoline had to be phased out eventually because it clogged catalytic converters on cars and led to more air pollution. Leaded gasoline manufacturers objected, but the objections were <a href="https://casetext.com/case/ethyl-corp-v-epa">overruled by an appeals court</a>. </p>
<p>The public health concerns continued to build in the 1970s and 1980s when University of Pittsburgh pediatrician Herbert Needleman ran studies linking high levels of lead in children with low IQ and other developmental problems. Both Patterson and Needleman faced strong partisan attacks from the lead industry, which <a href="http://www.beacon.org/Toxic-Truth-P662.aspx">claimed that their research was fraudulent</a>. </p>
<p>Both were eventually vindicated when, in 1996, the U.S. officially banned the sale of leaded gasoline for public health reasons. Europe was next in the 2000s, followed by developing nations after that. In August 2021, the last country in the world to sell leaded gas, Algeria, <a href="https://www.nationalgeographic.com/environment/article/finally-the-end-of-leaded-gas">banned it</a>.</p>
<p>A century of leaded gasoline has taken millions of lives and to this day leaves the soil in many cities from <a href="https://doi.org/10.1073/pnas.1906092116">New Orleans</a> to <a href="https://doi.org/10.1073/pnas.2102791118">London</a> toxic.</p>
<p>The leaded gasoline story provides a practical example of how industry’s profit-driven decisions – when unsuccessfully challenged and regulated – can cause serious and long-term harm. It takes individual public health leaders and strong media coverage of health and environmental issues to counter these risks. </p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-youresmart">You can read us daily by subscribing to our newsletter</a>.]</p><img src="https://counter.theconversation.com/content/173395/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bill Kovarik does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Burning leaded gasoline releases toxic lead into the environment, and for 100 years people around the world have been dealing with the health effects. How did a century of toxic fuel come to be?Bill Kovarik, Professor of Communication, Radford UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1637952021-07-30T12:22:48Z2021-07-30T12:22:48ZMale fertility is declining – studies show that environmental toxins could be a reason<figure><img src="https://images.theconversation.com/files/413819/original/file-20210729-15-sq2owv.jpg?ixlib=rb-1.1.0&rect=0%2C105%2C4345%2C3244&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">For decades, sperm counts and sperm health have been declining.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/sperm-cells-about-to-fertilize-an-ovum-new-life-royalty-free-image/1212523166?adppopup=true">Carol Yepes/Moment via Getty Images</a></span></figcaption></figure><p>In the U.S., nearly 1 in 8 couples <a href="https://www.nichd.nih.gov/health/topics/menshealth/conditioninfo/infertility#f1">struggles with infertility</a>. Unfortunately, physicians like me who specialize in reproductive medicine are unable to determine the cause of male infertility around <a href="https://doi.org/10.1016/s0140-6736(20)32667-2">30% to 50% of the time</a>. There is almost nothing more disheartening than telling a couple “I don’t know” or “There’s nothing I can do to help.” </p>
<p>Upon getting this news, couple after couple asks me questions that all follow a similar line of thinking. “What about his work, his cellphone, our laptops, all these plastics? Do you think they could have contributed to this?” </p>
<p>What my patients are really asking me is a big question in male reproductive health: Does environmental toxicity contribute to male infertility? </p>
<h2>Male fertility decline</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/413822/original/file-20210729-25-12sy39n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A medical professional sitting with a couple." src="https://images.theconversation.com/files/413822/original/file-20210729-25-12sy39n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/413822/original/file-20210729-25-12sy39n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413822/original/file-20210729-25-12sy39n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413822/original/file-20210729-25-12sy39n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413822/original/file-20210729-25-12sy39n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413822/original/file-20210729-25-12sy39n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413822/original/file-20210729-25-12sy39n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">If a couple is struggling to get pregnant, doctors will try to figure out the cause.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/doctor-consulting-with-patients-royalty-free-image/899796660?adppopup=true">Philippe Roy/Cultura via Getty Images</a></span>
</figcaption>
</figure>
<p>Infertility is defined as a couple’s inability to get pregnant for one year despite regular intercourse. When this is the case, doctors evaluate both partners to determine why.</p>
<p>For men, the cornerstone of the fertility evaluation is semen analysis, and there are a number of ways to assess sperm. Sperm count – the total number of sperm a man produces – and sperm concentration – number of sperm per milliliter of semen – are common measures, but they aren’t the <a href="https://doi.org/10.1093/humrep/dev058">best predictors of fertility</a>. A more accurate measure looks at <a href="https://doi.org/10.1093/humrep/dev058">the total motile sperm count</a>, which evaluates the fraction of sperm that are able to swim and move. </p>
<p>A wide range of factors – from <a href="https://doi.org/10.1016/s0140-6736(20)32667-2">obesity to hormonal imbalances to genetic diseases</a> – can affect fertility. For many men, there are <a href="https://doi.org/10.1016/s0140-6736(20)32667-2">treatments</a> that can help. But starting in the 1990s, researchers noticed a concerning trend. Even when controlling for many of the known risk factors, male fertility <a href="https://doi.org/10.1289/ehp.00108961">appeared to have been declining for decades</a>. </p>
<p>In 1992, a study found a global <a href="https://doi.org/10.1136/bmj.305.6854.609">50% decline in sperm counts in men over the previous 60 years</a>. Multiple studies over <a href="https://doi.org/10.1289/ehp.00108961">subsequent years</a> confirmed that initial finding, including a 2017 paper showing a <a href="https://doi.org/10.1093/humupd/dmx022">50% to 60% decline in sperm concentration between 1973 and 2011</a> in men from around the world. </p>
<p>These studies, though important, focused on sperm concentration or total sperm count. So in 2019, a team of researchers decided to focus on the more powerful total motile sperm count. They found that the proportion of men with a normal total motile sperm count <a href="https://doi.org/10.1016/j.urology.2019.06.038">had declined by approximately 10% over the previous 16 years</a>. </p>
<p>The science is consistent: Men today produce fewer sperm than in the past, and the sperm are less healthy. The question, then, is what could be causing this decline in fertility.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/413820/original/file-20210729-13-1bci2lm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A stack of reddish plastic pipes." src="https://images.theconversation.com/files/413820/original/file-20210729-13-1bci2lm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413820/original/file-20210729-13-1bci2lm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413820/original/file-20210729-13-1bci2lm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413820/original/file-20210729-13-1bci2lm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413820/original/file-20210729-13-1bci2lm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=567&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413820/original/file-20210729-13-1bci2lm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=567&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413820/original/file-20210729-13-1bci2lm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=567&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Plasticizers are common endocrine-disrupting compounds, found in many plastics – like PVC pipes – that come in contact with food or water.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Pvc_cevi.jpg#/media/File:Pvc_cevi.jpg">Mm Zaletel/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Environmental toxicity and reproduction</h2>
<p>Scientists have known for years that, at least in <a href="https://www.cdc.gov/biomonitoring/Phthalates_FactSheet.html">animal models</a>, environmental toxic exposure can alter hormonal balance and throw off reproduction. Researchers can’t intentionally expose human patients to harmful compounds and measure outcomes, but we can try to assess associations. </p>
<p>As the downward trend in male fertility emerged, I and other researchers began looking more toward chemicals in the environment for answers. This approach doesn’t allow us to definitively establish which chemicals are causing the male fertility decline, but the <a href="https://doi.org/10.21037/tau-20-685">weight of the evidence is growing</a>. </p>
<p>A lot of this research focuses on <a href="https://www.endocrine.org/topics/edc/what-edcs-are/common-edcs/reproduction">endocrine disrupters</a>, molecules that mimic the body’s hormones and <a href="https://doi.org/10.21037/tau-20-685">throw off the fragile hormonal balance of reproduction</a>. These include substances like phthalates – better known as plasticizers – as well as pesticides, herbicides, heavy metals, toxic gases and other synthetic materials. </p>
<p>Plasticizers are found in most plastics – like water bottles and food containers – and exposure is associated with <a href="https://doi.org/10.1016/j.envint.2018.07.029">negative impacts on testosterone and semen health</a>.
Herbicides and pesticides abound in the food supply and some – specifically those with synthetic organic compounds that include phosphorus – are <a href="https://doi.org/10.1016/j.toxlet.2014.01.029">known to negatively affect fertility</a>.</p>
<p>Air pollution surrounds cities, subjecting residents to particulate matter, sulfur dioxide, nitrogen oxide and other compounds that likely <a href="https://doi.org/10.1186/s12958-018-0430-2">contribute to abnormal sperm quality</a>. Radiation exposure from laptops, cellphones and modems has also been associated with <a href="https://doi.org/10.1186/s12958-018-0431-1">declining sperm counts, impaired sperm motility and abnormal sperm shape</a>. Heavy metals such as cadmium, lead and arsenic are also present in food, water and cosmetics and are also known to <a href="https://doi.org/10.1016/j.reprotox.2017.07.021">harm sperm health</a>.</p>
<p>Endocrine-disrupting compounds and the infertility problems they cause are taking a significant toll on human <a href="https://doi.org/10.1016/j.bpobgyn.2006.12.003">physical and emotional</a> health. And treating these harms <a href="https://doi.org/10.1210/jc.2014-4325">is costly</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414202/original/file-20210802-24-1jv2xsg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A sign warning of chemicals that cause cancer, birth defects or other reproductive harm." src="https://images.theconversation.com/files/414202/original/file-20210802-24-1jv2xsg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414202/original/file-20210802-24-1jv2xsg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414202/original/file-20210802-24-1jv2xsg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414202/original/file-20210802-24-1jv2xsg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414202/original/file-20210802-24-1jv2xsg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414202/original/file-20210802-24-1jv2xsg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414202/original/file-20210802-24-1jv2xsg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Thousands of new chemicals are introduced every year and government agencies do their best to keep up.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/prop-65-warning-posted-on-the-window-of-a-ventura-auto-news-photo/564054361?adppopup=true">Stephen Osman/Los Angeles Times via Getty Images</a></span>
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<h2>The effects of unregulated chemicals</h2>
<p>A lot of chemicals are in use today, and tracking them all is incredibly difficult. More than <a href="https://archive.epa.gov/oig/catalog/web/html/167.html">80,000 chemicals are registered in the U.S.</a> and nearly <a href="https://ntp.niehs.nih.gov/annualreport/2019/annualreport_508.pdf">2,000 new chemicals are introduced each year</a>. Many scientists believe that the safety testing for health and environmental risks <a href="https://theconversation.com/will-the-new-toxic-chemical-safety-law-protect-us-60769">is not strong enough</a> and that the rapid development and introduction of new chemicals challenges the ability of organizations to <a href="https://www.ewg.org/news-insights/news/top-problems-two-tsca-bills">test long-term risks to human health</a>.</p>
<p>Current U.S. regulations follow the principle of <a href="https://doi.org/10.1146/annurev-publhealth-031914-122654">innocent until proved guilty</a> and are <a href="https://doi.org/10.1289/ehp.0800404">less comprehensive and restrictive</a> than <a href="https://echa.europa.eu/home">similar regulations in Europe</a>, for example. The <a href="https://apps.who.int/iris/bitstream/handle/10665/78102/WHO_HSE_PHE_IHE_2013.1_eng.pdf?sequence=1">World Health Organization</a> recently identified 800 compounds capable of disrupting hormones, only a small fraction of which have been tested. </p>
<p>A trade group, the American Chemistry Council, says on its website that manufacturers “have the regulatory certainty they need to innovate, grow, create jobs and win in the global marketplace – at the same time that public health and the environment benefit from strong risk-based protections.” </p>
<p>But the reality of the current regulatory system in the U.S. is that chemicals are introduced with minimal testing and taken off the market only when harm is proved. And that can <a href="https://theconversation.com/will-the-new-toxic-chemical-safety-law-protect-us-60769">take decades</a>.</p>
<p>Dr. Niels Skakkebaek, the lead researcher on one of the <a href="https://www.newsweek.com/2017/09/22/male-infertility-crisis-experts-663074.html">first manuscripts</a> on decreasing sperm counts, called the male fertility decline a “wake-up call to all of us.” My patients have provided a wake–up call for me that increased public awareness and advocacy are important to protect global reproductive health now and in the future. I’m not a toxicologist and can’t identify the cause of the infertility trends I’m seeing, but as physician, I am concerned that too much of the burden of proof is falling on the human body and people who become my patients.</p>
<p><em>This article was updated to more accurately represent the chemical regulatory system in the U.S.</em></p><img src="https://counter.theconversation.com/content/163795/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan P. Smith receives funding from a Virginia Catalyst grant for male contraceptive research. </span></em></p>People are exposed to toxic substances – like pesticides, chemicals in plastics and radiation – every day. A growing body of research shows that this exposure is causing a decline in male fertility.Ryan P. Smith, Associate Professor of Urology, University of VirginiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1628392021-07-08T18:43:22Z2021-07-08T18:43:22ZEnvironmental racism: New study investigates whether Nova Scotia dump boosted cancer rates in nearby Black community<figure><img src="https://images.theconversation.com/files/410211/original/file-20210707-19-1sljla2.jpg?ixlib=rb-1.1.0&rect=25%2C32%2C4243%2C2805&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Environmentally dangerous dumps, landfills and pulp and paper mills are more likely to be sited in African Nova Scotian and Mi'kmaw communities. These communities suffer from high rates of cancer and respiratory illness.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>In the 1940s, the town of Shelburne, N.S., became home to a new garbage dump. Residential, industrial and medical waste from throughout eastern Shelburne County <a href="https://www.saltwire.com/atlantic-canada/communities/southwest-nova-scotia/former-shelburne-town-dumpsite-a-ticking-timebomb-in-the-black-community-says-seed-100587217/">was burned at the dump</a> over the decades, leaving nearby residents concerned about health issues. </p>
<p>The dump was situated uphill from the African Nova Scotian South End community, whose roots date back to the <a href="https://novascotia.ca/museum/blackloyalists/communities.htm">settlement of Black Loyalists who were evacuated from the United States after the Revolutionary War of 1776</a>. Those near the dump worked, played and lived amid constant smells and smoke from burning garbage. The dump operated for 75 years, closing in 2016.</p>
<p>The placement of this dump was an act of what we now refer to as environmental racism — the disproportionate siting of polluting industries and other environmentally hazardous projects in Indigenous, Black and other marginalized communities.</p>
<p>Questions about the high rates of cancer — and deaths — among members of Shelburne’s African Nova Scotian community, compared to their white neighbours on the other side of town or even within the South End, have <a href="https://www.cbc.ca/radio/thecurrent/features/facing-race/a-community-of-widows-how-african-nova-scotians-are-confronting-a-history-of-environmental-racism-1.4497952">long simmered</a>. We, along with our colleagues, are embarking on a major research project to determine whether the legacy of the dump may be even more sinister than people knew at the time.</p>
<h2>Community-based research on environmental racism</h2>
<p>Much of the motivation for the study comes from the work of local activist Louise Delisle, who has gone door-to-door in her community to catalogue cases of cancer, both recent and historical. </p>
<p>Previous and ongoing research and advocacy conducted through the Environmental Noxiousness, Racial Inequities & Community Health Project (<a href="https://www.enrichproject.org">the ENRICH Project</a>), data in the book <em><a href="https://fernwoodpublishing.ca/book/there8217s-something-in-the-water">There’s Something in the Water: Environmental Racism in Indigenous & Black Communities</a></em> and experiences of environmental racism shared by Nova Scotian community members in the <a href="https://www.netflix.com/ca/title/81206890">Netflix documentary of the same name</a>, confirm the necessity for such an investigation. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/410205/original/file-20210707-27-1ypevgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing communities and toxic facilities in Nova Scotia" src="https://images.theconversation.com/files/410205/original/file-20210707-27-1ypevgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410205/original/file-20210707-27-1ypevgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410205/original/file-20210707-27-1ypevgb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410205/original/file-20210707-27-1ypevgb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410205/original/file-20210707-27-1ypevgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410205/original/file-20210707-27-1ypevgb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410205/original/file-20210707-27-1ypevgb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Locations of African Nova Scotian communities, First Nations communities and toxic facilities in Nova Scotia.</span>
<span class="attribution"><a class="source" href="https://www.enrichproject.org/map/">(ENRICH Project)</a></span>
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<p>The data collected by the ENRICH Project over the years indicate that environmentally dangerous projects like dumps, landfills and pulp and paper mills are more likely to be sited in African Nova Scotian and Mi'kmaw communities, and that these communities suffer from high rates of cancer and respiratory illness.</p>
<p>Momentum to address environmental racism is also growing. A federal private member’s bill introduced by Nova Scotia MP Lenore Zann, the <a href="https://www.parl.ca/DocumentViewer/en/43-1/bill/C-230/first-reading">National Strategy to Redress Environmental Racism</a>, passed second reading on March 24, 2021. </p>
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<strong>
Read more:
<a href="https://theconversation.com/bill-c-230-marks-an-important-first-step-in-addressing-environmental-racism-in-canada-158686">Bill C-230 marks an important first step in addressing environmental racism in Canada</a>
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<p>Bill C-230 returned to the federal Standing Committee on Environment and Sustainable Development on June 21 for amendments, where it was approved a few days later. It will move to third reading in the fall of 2021, and then to the Senate, after which it may become Canada’s first legislation to address environmental racism. </p>
<h2>Many factors influence cancer</h2>
<p>As many factors can influence the incidence of cancer within a population, we’ll oversee a team spanning several research disciplines, with McMaster University serving as the hub and significant representation from Dalhousie University, co-ordinated by cancer biologist Paola Marignani.</p>
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<figcaption><span class="caption">‘There’s Something in the Water’ official trailer.</span></figcaption>
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<p>Environmental chemical exposures, such as polychlorinated biphenyls (PCBs), can interact with biological and genetic factors, as well as <a href="https://www.cpha.ca/what-are-social-determinants-health">social determinants of health</a>, such as <a href="https://research2reality.com/health-medicine/health-data-black-canadian-women-cancer-risks/">access to health care, race, gender and income</a>, and lifestyle factors, such as diet, physical activity and smoking. </p>
<p>Our team will probe the contents of the dump to identify harmful materials such as heavy metals, volatile organic compounds and fine particulate matter, and we will examine genetic and epigenetic changes to the genomes of Shelburne residents that may explain cancer susceptibility. </p>
<p>We will also examine the extent to which <a href="https://www.canada.ca/content/dam/phac-aspc/documents/services/health-promotion/population-health/what-determines-health/social-determinants-inequities-black-canadians-snapshot/health-inequities-black-canadians.pdf">race</a>, <a href="http://pressroom.cancer.org/SocialDeterminants2019">gender, income</a> and other <a href="https://familyreach.org/blog/how-do-social-determinants-of-health-affect-cancer-patients/">social determinants of health contribute to cancer and premature death</a>. The role of diet, exercise, smoking and other <a href="https://www.pennmedicine.org/cancer/navigating-cancer-care/risks-and-prevention/lifestyle-risk-factors">lifestyle factors</a> in cancer incidence in Shelburne will also be studied given that <a href="https://www.healthlinkbc.ca/health-topics/abj7482">existing studies indicate that these factors can increase our likelihood of getting cancer</a>. </p>
<h2>Cancer in Black communities</h2>
<p>The study is multidisciplinary and complex. Yet we are confident it will help clarify the complex interactions between the social determinants of health, lifestyle factors, genetics and <a href="https://doi.org/10.1007/978-1-4419-9967-2_11">generational impact of chronic toxin exposure</a>. It will also shed light on what is driving high cancer rates in South End Shelburne. </p>
<p>Our study will not just have value for the small community of Shelburne but will provide a template for further studies on the relationship between environmental racism and chronic diseases. For example, the African Nova Scotian community in <a href="https://halifaxmag.com/cityscape/17948/">Lincolnville, N.S.</a>, Indigenous communities such as <a href="https://thenarwhal.ca/covid-19-environmental-racism-canada/">Wet'suwet'en First Nation in northern B.C.</a>, and <a href="https://anishinabeknews.ca/2021/07/02/new-environmental-study-underway-this-summer-in-aamjiwnaang-first-nation/">Aamjiwnaang First Nation near Sarnia, Ont.</a>, as well as African Americans living near <a href="https://www.propublica.org/article/welcome-to-cancer-alley-where-toxic-air-is-about-to-get-worse">Cancer Alley in Louisiana</a>, who all live close to landfills, pipelines and petrochemical facilities, could all benefit from a similar multidisciplinary approach. </p>
<p>This study, and others like it, will bring us one step closer to addressing the wider problem of systemic racism in Canada.</p><img src="https://counter.theconversation.com/content/162839/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ingrid Waldron receives funding from New Frontiers in Research Fund, CIHR, and SSHRC</span></em></p><p class="fine-print"><em><span>Juliet Daniel receives funding from CIHR, NSERC and New Frontiers Research Fund (NFRF).</span></em></p>Black residents of Shelburne, N.S., spent decades living near a dump, worrying about its possible connection to elevated cancer rates. A new study will investigate the dump’s long-term consequences.Ingrid Waldron, Professor, Faculty of Humanities, HOPE Chair in Peace & Health, McMaster UniversityJuliet Daniel, Professor, Department of Biology, McMaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1439792020-08-05T04:46:47Z2020-08-05T04:46:47ZWhat is ammonium nitrate, the chemical that exploded in Beirut?<p>The Lebanese capital Beirut <a href="https://www.theguardian.com/world/live/2020/aug/04/beirut-explosion-huge-blast-port-lebanon-capital">was rocked</a> on Tuesday evening local time by an explosion that has killed at least 78 people and injured thousands more.</p>
<p>The country’s prime minister Hassan Diab said the blast was caused by around 2,700 tonnes of ammonium nitrate stored near the city’s cargo port. Video footage appears to show a <a href="https://www.npr.org/2020/08/04/898969935/massive-explosion-rocks-beirut-damaging-buildings-and-shattering-windows">fire</a> burning nearby before the blast. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1290672351844196352"}"></div></p>
<p>Ammonium nitrate has the chemical formula NH₄NO₃. Produced as small porous pellets, or “prills”, it’s one of the world’s most widely used fertilisers. </p>
<p>It is also the main component in many types of mining explosives, where it’s mixed with fuel oil and detonated by an explosive charge.</p>
<p>For an industrial ammonium nitrate disaster to occur, a lot needs to go wrong. Tragically, this seems to have been the case in Beirut. </p>
<h2>What could have caused the explosion?</h2>
<p>Ammonium nitrate does not burn on its own. </p>
<p>Instead, it acts as a source of oxygen that can accelerate the <a href="https://www.bbc.co.uk/bitesize/topics/zypsgk7/articles/zcwxcj6">combustion</a> (burning) of other materials. </p>
<p>For combustion to occur, oxygen must be present. Ammonium nitrate prills provide a much more concentrated supply of oxygen than the air around us. This is why it is effective in mining explosives, where it’s mixed with oil and other fuels.</p>
<p>At high enough temperatures, however, ammonium nitrate can violently decompose on its own. This process creates gases including nitrogen oxides and water vapour. It is this rapid release of gases that causes an explosion. </p>
<p>Ammonium nitrate decomposition can be set off if an explosion occurs where it’s stored, if there is an intense fire nearby. The latter is what happened in the 2015 <a href="https://www.bbc.com/news/world-asia-china-37927158">Tianjin explosion</a>, which killed 173 people after flammable chemicals and ammonium nitrate were stored together at a chemicals factory in eastern China.</p>
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Read more:
<a href="https://theconversation.com/explainer-how-dangerous-is-the-sodium-cyanide-found-at-tianjin-explosion-site-46229">Explainer: how dangerous is the sodium cyanide found at Tianjin explosion site?</a>
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<p>While we don’t know for sure what caused the explosion in Beirut, footage of the incident indicates it may have been set off by a fire – visible in a section of the city’s port area before the explosion happened. </p>
<p>It’s relatively difficult for a fire to trigger an ammonium nitrate explosion. The fire would need to be sustained and confined within the same area as the ammonium nitrate prills. </p>
<p>Also, the prills themselves are not fuel for the fire, so they would need to be contaminated with, or packaged in, some other combustible material.</p>
<h2>Residents’ health at risk</h2>
<p>In Beirut, it has been reported 2,700 tonnes of ammonium nitrate were <a href="https://www.theguardian.com/world/live/2020/aug/04/beirut-explosion-huge-blast-port-lebanon-capital">stored in a warehouse</a> for six years without proper safety controls.</p>
<p>This will almost certainly have contributed to the tragic circumstances that resulted in a commonplace industrial fire causing such a devastating explosion.</p>
<p>An ammonium nitrate explosion produces massive amounts of <a href="https://www.abc.net.au/news/2020-06-15/bright-orange-mine-blast-concerns-residents/12332224">nitrogen oxides</a>. Nitrogen dioxide (NO₂) is a red, bad-smelling <a href="https://www.abc.net.au/news/2020-06-15/bright-orange-mine-blast-concerns-residents/12332224">gas</a>. Images from Beirut reveal a distinct reddish colour to the plume of gases from the blast. </p>
<p>Nitrogen oxides are commonly present in urban air pollution, and can irritate the respiratory system. Elevated levels of these pollutants are particularly concerning for people with respiratory conditions.</p>
<p>The fumes in Beirut will present a health risk to residents until they naturally dissipate, which could take several days depending on the local weather. </p>
<h2>An important reminder</h2>
<p>Here in Australia, we produce and import large amounts of ammonium nitrate, mostly for use in mining. It is made by combining <a href="https://www.britannica.com/science/ammonia">ammonia</a> gas with liquid nitric acid, which itself is made from ammonia.</p>
<p>Ammonium nitrate is classified as <a href="http://www.dmp.wa.gov.au/Dangerous-Goods/What-is-a-dangerous-good-4411.aspx">dangerous goods</a> and all aspects of its use are tightly regulated. For decades, Australia has produced, stored and used ammonium nitrate without a <a href="https://www.abc.net.au/news/2014-09-07/ammonium-nitrate-truck-explosion-site/5725904?nw=0"><em>major</em></a> incident. </p>
<p>The explosion in Beirut shows us just how important these regulations are.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/75-years-after-hiroshima-and-nagasaki-the-vatican-is-providing-moral-guidance-on-nuclear-weapons-140615">75 years after Hiroshima and Nagasaki, the Vatican is providing moral guidance on nuclear weapons</a>
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<img src="https://counter.theconversation.com/content/143979/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gabriel da Silva does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>For combustion to occur, oxygen must be present. Ammonium nitrate prills provide a much more concentrated supply of oxygen than the air around us.Gabriel da Silva, Associate Professor of Chemical Engineering, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1410422020-07-09T04:02:08Z2020-07-09T04:02:08Z‘Living fossils’: we mapped half a billion years of horseshoe crabs to save them from blood harvests<figure><img src="https://images.theconversation.com/files/345986/original/file-20200707-27858-x1kgcv.jpg?ixlib=rb-1.1.0&rect=15%2C0%2C5160%2C3445&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>If you ventured to the New York seaside in summer, you might see a large dome-shaped animal with a spiky tail, slowly moving towards the water. These are horseshoe crabs – the animals time forgot.</p>
<p>Fossil records for horseshoe crabs extend back about 480 million years. This is well over 200 million years before the dinosaurs. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-giant-species-of-trilobite-inhabited-australian-waters-half-a-billion-years-ago-118452">A giant species of trilobite inhabited Australian waters half a billion years ago</a>
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<p>More recently, horseshoe crabs have greatly helped advance modern medicine. Their blood is used to identify <a href="https://www.sciencedirect.com/topics/chemistry/endotoxin">endotoxins</a> in solutions. These are toxins found in bacteria, so anyone who has had an injection or surgery has been kept safe from dangerous toxins thanks to these creatures.</p>
<p>Unfortunately, the harvesting of their blood for this purpose is one reason horseshoe crabs are becoming an <a href="https://science.howstuffworks.com/life/biology-fields/horseshoe-crabs-endangered-biomedical-bloodletting.htm">endangered group</a>. Our <a href="https://www.frontiersin.org/articles/10.3389/feart.2020.00098/abstract">research</a> published today in Frontiers in Earth Science will hopefully aid conservation efforts to protect these enigmatic creatures.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/342637/original/file-20200618-41200-1grm5ca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/342637/original/file-20200618-41200-1grm5ca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/342637/original/file-20200618-41200-1grm5ca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/342637/original/file-20200618-41200-1grm5ca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/342637/original/file-20200618-41200-1grm5ca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/342637/original/file-20200618-41200-1grm5ca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/342637/original/file-20200618-41200-1grm5ca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The American horseshoe crab <em>Limulus polyphemus</em>.</span>
<span class="attribution"><span class="source">WikiCommons.</span></span>
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</figure>
<h2>A modern medical marvel</h2>
<p>Completely harmless, but spiky like a cactus, horseshoe crabs are not actually crabs. They don’t have the antennae or jaws their crustacean cousins do, and have additional pairs of legs (13 in total). In fact, they’re more closely related to spiders and scorpions than crabs. </p>
<p>Defined within their own order, <a href="https://ucmp.berkeley.edu/arthropoda/chelicerata/xiphosura.html">Xiphosura</a>, these animals are characterised by a horseshoe-shaped head section, a roundish hexagonal backside and a long tail. They are, in essence, a spider in a suit of armour that can swim upside down. </p>
<p>Horseshoe crabs have been used in medicine for at least the <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2006607">past 40 years</a>. Their endotoxin-revealing blood is blue and copper-based (unlike our red, iron-based blood). </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/blood-in-your-veins-is-not-blue-heres-why-its-always-red-97064">Blood in your veins is not blue – here's why it's always red</a>
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<p>A chemical refined from their blood can be used to identify contaminants in medical equipment that is inserted into <a href="https://www.iflscience.com/plants-and-animals/how-horseshoe-crab-blood-saves-millions-lives/">humans</a>. </p>
<p>Blue blood is used to make sure injections, IV drips, and any implanted medical devices are safe for human use.</p>
<h2>Blue bloodletting</h2>
<p>However, to access this natural medicinal miracle, humans must collect horseshoe crabs and harvest their blood. While blood loss itself may not be the main cause of death, other factors such as capture and transport can impact group survival. </p>
<p>At present, with improved practices, between <a href="https://www.frontiersin.org/articles/10.3389/fmars.2018.00185/full?utm_source=FWEB&utm_medium=NBLOG&utm_campaign=ECO_FMARS_horseshoe-crab-blood#h11">6-15.4% </a> of horseshoe crabs die from harvesting.</p>
<p>This process represents one of the main threats to them today, even though a <a href="https://www.theatlantic.com/science/archive/2018/05/blood-in-the-water/559229/">synthetic substitute</a> for blue blood has been available for nearly two decades. However, there is uncertainty around the efficacy of this alternative, so horseshoe crabs are <a href="https://blogs.unimelb.edu.au/sciencecommunication/2019/10/22/horseshoe-crab-the-blue-blood-that-saves-millions-of-lives/">still harvested</a>.</p>
<p>As a result, two of the four living species – the Chinese horseshoe crab and American horseshoe crab (also called the Atlantic horseshoe crab) – have been placed on the <a href="https://www.iucnredlist.org/search?taxonomies=101493&searchType=species">International Union for Conservation of Nature’s</a> vulnerable and endangered species list.</p>
<p>Apart from bloodletting for biomedical use, <a href="https://www.nwf.org/Educational-Resources/Wildlife-Guide/Invertebrates/Horseshoe-Crab">other threats</a> facing horseshoe crabs include overharvesting, <a href="https://www.sciencedirect.com/science/article/pii/S2351989419306997">human interaction and serious habitat modification</a>.</p>
<h2>Fantastic beasts, and where to find them (online)</h2>
<p>To help raise awareness about the challenges horseshoe crabs face, we created an <a href="https://www.frontiersin.org/articles/10.3389/feart.2020.00098/abstract">atlas of all fossil and living Xiphosura</a>. This free, open access collection contains photos of every horseshoe crab species ever described in the group’s 480-million-year history. </p>
<p>Alongside the photos, we provide outlines of how the four living species survived until now. </p>
<p>Building this atlas took three years. It involved emailing more than 100 researchers and museum managers, and even travelling from Australia to England, Germany, Russia, Slovenia and the United States to collect photographs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/342937/original/file-20200619-70381-16myyr1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/342937/original/file-20200619-70381-16myyr1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/342937/original/file-20200619-70381-16myyr1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=241&fit=crop&dpr=1 600w, https://images.theconversation.com/files/342937/original/file-20200619-70381-16myyr1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=241&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/342937/original/file-20200619-70381-16myyr1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=241&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/342937/original/file-20200619-70381-16myyr1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=302&fit=crop&dpr=1 754w, https://images.theconversation.com/files/342937/original/file-20200619-70381-16myyr1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=302&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/342937/original/file-20200619-70381-16myyr1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=302&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Examples of fossil horseshoe crabs. Left to right: <em>Pickettia carteri</em>, <em>Albalimulus bottoni</em>, <em>Sloveniolimulus rudkini</em>, and <em>Tasmaniolimulus patersoni</em>.</span>
<span class="attribution"><span class="source">Reconstructions by Elissa Johnson and Katrina Kenny</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The result is an example of every single horseshoe crab species ever documented, living or extinct – more than 110 in total.</p>
<h2>The ‘living fossil’ that roamed with dinosaurs</h2>
<p>Our atlas can help highlight the unique and complex evolutionary history of horseshoe crabs. </p>
<p>These arthropods (invertebrates with an exoskeleton and jointed legs) survived all mass extinctions. Some have changed in appearance through time. For example, we have completely bizarre fossil forms, such as <em>Austrolimulus</em> – essentially a pick-axe in horseshoe crab form.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/342654/original/file-20200618-41221-18cmqhd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/342654/original/file-20200618-41221-18cmqhd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=440&fit=crop&dpr=1 600w, https://images.theconversation.com/files/342654/original/file-20200618-41221-18cmqhd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=440&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/342654/original/file-20200618-41221-18cmqhd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=440&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/342654/original/file-20200618-41221-18cmqhd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=553&fit=crop&dpr=1 754w, https://images.theconversation.com/files/342654/original/file-20200618-41221-18cmqhd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=553&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/342654/original/file-20200618-41221-18cmqhd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=553&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Austrolimulus fletcheri</em> lived in the New South Wales area during the Triassic. They’re a truly unique species.</span>
<span class="attribution"><span class="source">Patrick Smith.</span></span>
</figcaption>
</figure>
<p>However, some fossil species look very similar to modern ones. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/342656/original/file-20200618-41242-hdtdm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/342656/original/file-20200618-41242-hdtdm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=973&fit=crop&dpr=1 600w, https://images.theconversation.com/files/342656/original/file-20200618-41242-hdtdm7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=973&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/342656/original/file-20200618-41242-hdtdm7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=973&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/342656/original/file-20200618-41242-hdtdm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1223&fit=crop&dpr=1 754w, https://images.theconversation.com/files/342656/original/file-20200618-41242-hdtdm7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1223&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/342656/original/file-20200618-41242-hdtdm7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1223&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Mesolimulus walchi</em>, from the Solnhofen Limestone in Germany.</span>
<span class="attribution"><span class="source">Russell Bicknell/Paläontologisches Museum, München specimen.</span></span>
</figcaption>
</figure>
<p>Compare the Jurassic-aged fossil <em>Mesolimulus</em>, found in <a href="https://en.wikipedia.org/wiki/Solnhofen_Limestone">Solnhofen Limestone</a> in Germany, to American horseshoe crabs walking along the North American coast today. They are practically the same. </p>
<p>Apart from size differences, horseshoes crabs have changed very little over the past 150 million years or so, earning them the moniker “living fossils”. But while specimens in the fossil record are between 3-30cm long, horseshoe crabs today can grow to more than 80cm.</p>
<p>Unfortunately, horseshoe crab populations have been decreasing significantly due to blood harvesting. There’s now <a href="https://www.theguardian.com/environment/2018/nov/03/horseshoe-crab-population-at-risk-blood-big-pharma">genuine concern</a> humans will drive these organisms to extinction.</p>
<p>Expanding our collective knowledge could help fuel future conservation efforts. Let’s prevent these unique icons of a bygone era from passing into the annals of history. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/giant-sea-scorpions-were-the-underwater-titans-of-prehistoric-australia-141290">Giant sea scorpions were the underwater titans of prehistoric Australia</a>
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</em>
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<img src="https://counter.theconversation.com/content/141042/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Russell Dean Christopher Bicknell received funding for this project in the following forms: a University of New England Post Doctoral Fellowship, Betty Mayne Scientific Research Fund, James R Welch Scholarship, and a Schuchert and Dunbar Grants in Aid Program. He is also a member of the International Union for the Conservation of Nature Horseshoe Crab Species Specialist Group.
</span></em></p><p class="fine-print"><em><span>Stephen Pates is a postdoctoral fellow funded by the Museum of Comparative Zoology, Harvard University.</span></em></p>A chemical refined from the blue, copper-based blood of horseshoe crabs helps identify contaminants in medical equipment inserted into humans.Russell Dean Christopher Bicknell, Post-doctoral researcher in Palaeobiology , University of New EnglandStephen Pates, Postdoctoral fellow, Harvard UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1246302019-12-20T16:56:16Z2019-12-20T16:56:16ZHangovers happen as your body tries to protect itself from alcohol’s toxic effects<figure><img src="https://images.theconversation.com/files/308125/original/file-20191220-11904-o6bx4v.jpg?ixlib=rb-1.1.0&rect=365%2C121%2C4409%2C3063&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A night of revelry can mean an uncomfortable day after.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/migraine-headache-227278786">Everett Collection/Shutterstock.com</a></span></figcaption></figure><p>Debaucherous evening last night? You’re probably dealing with veisalgia right now.</p>
<p>More commonly known as a hangover, this unpleasant phenomenon <a href="https://time.com/3958046/history-of-hangovers/">has been dogging humanity</a> since our ancestors first happened upon fermentation.</p>
<p>Those nasty vertigo-inducing, cold sweat-promoting and vomit-producing sensations after a raucous night out are all part of your body’s attempt to protect itself from injury after you overindulge in alcoholic beverages. Your liver is working to break down the alcohol you consumed so your kidneys can clear it out ASAP. But in the process, your body’s inflammatory and metabolic reactions are going to lay you low with a hangover.</p>
<p>As long as people have suffered from hangovers, they’ve searched in vain for a cure. Revelers have access to a variety of compounds, products and devices that purport to ease the pain. But there’s a lot of purporting and not a lot of proof. Most have not been backed up well by science in terms of usefulness for hangover treatment, and often their effects don’t seem like they’d match up with what scientists know about the biology of the hangover.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308010/original/file-20191219-11900-1nrkesq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308010/original/file-20191219-11900-1nrkesq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308010/original/file-20191219-11900-1nrkesq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308010/original/file-20191219-11900-1nrkesq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308010/original/file-20191219-11900-1nrkesq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308010/original/file-20191219-11900-1nrkesq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308010/original/file-20191219-11900-1nrkesq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308010/original/file-20191219-11900-1nrkesq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Drain enough cups of booze in one session and you know what’s bound to follow.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/EEIIm23ktS4">Laura buron/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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</figure>
<h2>Working overtime to clear out the booze</h2>
<p>Hangovers are virtually guaranteed when you drink too much. That amount varies from person to person based on <a href="https://doi.org/10.1111/add.12699">genetic factors</a> as well as whether there are <a href="https://doi.org/10.1111/j.1530-0277.2009.01116.x">other compounds</a> that formed along with ethanol in the fermentation process.</p>
<p>Over the course of a night of heavy drinking, your blood alcohol level continues to rise. Your body labors to break down the alcohol – consumed as ethanol in beer, wine or spirits – forming damaging oxygen free radicals and acetaldehyde, itself a harmful compound. The longer ethanol and acetaldehyde stick around, the more damage they can do to your cellular membranes, proteins and DNA, so your body’s enzymes work quickly to metabolize acetaldehyde to a less toxic compound, acetate.</p>
<p>Over time, your ethanol levels drop through this natural metabolic process. Depending on how much you consumed, you’re likely to experience a hangover as the level of ethanol in your blood slowly returns to zero. Your body is withdrawing from high levels of circulating alcohol, while at the same time trying to protect itself from the effects of alcohol.</p>
<p>Scientists have limited knowledge of the leading causes of the hangover. But they do know that the body’s responses include changes in hormone levels to <a href="https://www.pulsus.com/abstract/alcohol-hangover-its-effects-on-human-body-review-4404.html">reduce dehydration</a> and cellular stress. Alcohol consumption also affects a variety of <a href="https://doi.org/10.1093/alcalc/agz016">neurotransmitter systems</a> in the brain, including glutamate, dopamine and serotonin. Inflammation increases in the body’s tissues, and the healthy gut bacteria in your digestive system take a hit too, promoting <a href="https://doi.org/10.1093/alcalc/agy061">leaky gut</a>.</p>
<p>Altogether, <a href="https://doi.org/10.1093/alcalc/agz016">the combination of all these reactions</a> and protective mechanisms activated by your system gives rise to the experience of a hangover, which can last up to 48 hours.</p>
<h2>Your misery likely has company</h2>
<p>Drinking and socializing are cultural acts, and most hangovers <a href="https://doi.org/10.1080/13676261.2012.693594">do not happen in isolation</a>. Human beings are social creatures, and there’s a high likelihood that at least one other individual feels the same as you the morning after the night before.</p>
<p>Each society has different rules regarding alcohol use, which can affect how people <a href="https://doi.org/10.1016/j.puhe.2011.09.014">view alcohol consumption within those cultures</a>. Drinking is often valued for its relaxing effect and for promoting sociability. So it’s common to see alcohol provided at celebratory events, social gatherings and holiday parties.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/308014/original/file-20191219-11939-1p3ym3k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308014/original/file-20191219-11939-1p3ym3k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/308014/original/file-20191219-11939-1p3ym3k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=638&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308014/original/file-20191219-11939-1p3ym3k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=638&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308014/original/file-20191219-11939-1p3ym3k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=638&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308014/original/file-20191219-11939-1p3ym3k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=802&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308014/original/file-20191219-11939-1p3ym3k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=802&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308014/original/file-20191219-11939-1p3ym3k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=802&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">For many people, ‘partying’ is synonymous with ‘drinking.’</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/BnzqQwerUOY">Lidya Nada/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>In the United States, drinking alcohol is largely embraced by mainstream culture, which may even promote behaviors involving <a href="https://doi.org/10.1186/1471-2458-9-51">excessive drinking</a>. It should be no surprise that overindulgence goes hand in hand with these celebratory social events – and leads to hangover regrets a few hours later. </p>
<p>Your body’s reactions to high alcohol intake and the sobering-up period can influence mood, too. The combination of fatigue that you experience from sleep deprivation and hormonal stress reactions, in turn, affect your neurobiological responses and behavior. As your body is attempting to repair itself, you’re more likely to be easily irritated, exhausted and want nothing more than to be left alone. Of course, your <a href="https://doi.org/10.2174/1874473711003020080">work productivity takes a dramatic hit</a> the day after an evening of heavy drinking.</p>
<p>When all is said and done, you’re the cause of your own hangover pain, and you’re the one who must pay for all the fun of the night before. But in short order, you’ll <a href="https://doi.org/10.1016/j.addbeh.2008.06.014">forget how excruciating your last hangover</a> was. And you may very soon talk yourself into doing the things you swore you’d never do again.</p>
<h2>Speeding up recovery</h2>
<p>While pharmacologists <a href="https://scholar.google.com/citations?user=miPd9ysAAAAJ&hl=en&oi=ao">like</a> <a href="https://scholar.google.com/citations?user=ZLL4yjwAAAAJ&hl=en&oi=ao">us</a> understand a bit about how hangovers work, we still lack a true remedy.</p>
<p>Countless articles describe a <a href="http://www.cjhp.org/volume16Issue1_2018/documents/79-90_CJHP2018Issue1_Kruger.pdf">variety of foods</a>, caffeine, ion replenishment, <a href="https://doi.org/10.1016/j.neulet.2018.01.030">energy drinks</a>, <a href="https://www.ncbi.nlm.nih.gov/pubmed/30462386">herbal supplements</a> including <a href="https://doi.org/10.3390/molecules21010064">thyme and ginger, vitamins</a> and the “hair of the dog” as ways to <a href="https://doi.org/10.1002/hup.2600">prevent and treat hangovers</a>. But the evidence isn’t really there that any of these work effectively. They’re just not scientifically validated or well reproduced.</p>
<p>For example, Kudzu root (<em>Pueraria lobata</em>), a popular choice for hangover remedies, has primarily been investigated for its effects in reducing alcohol-mediated stress and hangover. But at the same time, Kudzu root appears to <a href="https://doi.org/10.1016/j.alcohol.2007.07.009">inhibit the enzymes that break down acetaldehyde</a> – not good news since you want to clear that acetaldehyde from your system quickly.</p>
<p>To fill this knowledge gap, our lab is <a href="https://pharmacyschool.usc.edu/directory/?expert=jing.liangphd">working with colleagues</a> to see if we can find scientific evidence for or against potential hangover remedies. We’ve focused on the benefits of dihydromyricetin, a Chinese herbal medicine that is currently available and formulated as a dietary supplement for hangover reduction or prevention.</p>
<p>Dihydromyricetin appears to work its magic by <a href="https://www.ncbi.nlm.nih.gov/pubmed/17048612">enhancing alcohol metabolism</a> and reducing its toxic byproduct, acetaldehyde. From our findings in mice models, we are collecting data that support the usefulness of dihydromyricetin in <a href="http://www.koreascience.or.kr/article/JAKO200003042335835.page">increasing the expression and activity of enzymes</a> responsible for ethanol and acetaldehyde metabolism in the liver, where ethanol is primarily broken down. These findings explain one of the several ways dihydromyricetin protects the body against alcohol stress and hangover symptoms. </p>
<p>We are also studying how this enhancement of alcohol metabolism results in changes in alcohol drinking behaviors. Previously, dihydromyricetin was found to counteract the relaxation affect of drinking alcohol by interfering with particular neuroreceptors in the brain; <a href="https://doi.org/10.1523/JNEUROSCI.4639-11.2012">rodents didn’t become as intoxicated</a> and consequently reduced their ethanol intake. Through this combination of mechanisms, we hope to illustrate how DHM might reduce the downsides of excessive drinking beyond the temporary hangover, and potentially reduce drinking behavior and damage associated with heavy alcohol consumption.</p>
<p>Of course, limiting alcohol intake and substituting water for many of those drinks during an evening out is probably the best method to avoid a painful hangover. However, for those times when one alcoholic beverage leads to more than a few more, be sure to stay hydrated and catch up on rest. Your best bet for a smoother recovery is probably some combination of <a href="https://doi.org/10.1016/j.alcohol.2019.10.006">nonsteroidal anti-inflammatory drug</a> like ibuprofen, Netflix and a little downtime. </p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/124630/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Davies received a Donation from 82 Labs two years ago to conduct basic research on DHM that is mentioned in the article. </span></em></p><p class="fine-print"><em><span>Joshua Silva and Terry David Church do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Researchers know the basic biology of what happens to your system after a night of heavy drinking. Unfortunately, evidence-based cures for the common hangover are still at the investigation stage.Daryl Davies, Professor of Clinical Pharmacy, University of Southern CaliforniaJoshua Silva, Ph.D. Candidate in Clinical and Experimental Therapeutics, University of Southern CaliforniaTerry David Church, Assistant Professor of Regulatory and Quality Sciences, University of Southern CaliforniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1255852019-10-31T14:46:43Z2019-10-31T14:46:43ZWe studied mercury levels in Cape monkfish off Namibia’s coast<figure><img src="https://images.theconversation.com/files/298513/original/file-20191024-170449-9j284o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Consumers should bear in mind that the bigger the fish, the more likely that it will have a high concentration of mercury. </span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The presence of mercury in the marine environment is becoming an issue of concern. Once in the ocean mercury is <a href="https://www.ncbi.nlm.nih.gov/pubmed/14757716">converted</a> into a more toxic compound known as methylmercury. In this form it’s absorbed by the digestive tract of creatures at <a href="https://pdfs.semanticscholar.org/c178/fcd7e6fe4db6d76db9b211249f5e3d54207e.pdf?_ga=2.73234325.761941332.1571749086-1262164574.1569500172">all feeding levels</a> in the marine ecosystem. In fish, reduced swimming activity, loss of balance, and possibly death have been linked to <a href="https://www.sciencedirect.com/science/article/pii/S0022098196025907">mercury contamination</a>. Mercury has a very low rate of breakdown and excretion, which means it builds up – in a process known as bioaccumulation – through the entire food chain.</p>
<p>We conducted <a href="https://www.ncbi.nlm.nih.gov/pubmed/30301008">research</a> to establish the levels of mercury in Cape monkfish, a <a href="https://www.tandfonline.com/doi/abs/10.2989/18142320509504090">commercially important fish species</a> off the Namibian coast. This species also plays a <a href="https://link.springer.com/article/10.1007/BF00004906">key ecological role</a> in the marine ecosystem. It feeds on other fishes and so regulates various fish populations.</p>
<p>The two conditions in which we found higher levels of mercury concentration were in larger fish and in fish in deeper waters. Some fish (0.57%) had higher levels of mercury above the World Health Organisation limit of 0.5mg/kg. However, most of the fish had mercury levels still below the World Health Organisation limit of 0.5mg/kg. </p>
<p>Our findings are important because although the Cape monkfish isn’t currently a risk to humans who eat it, this may change because of future industrial development in the region. </p>
<h2>What we found</h2>
<p>Cape monkfish is an important food source in Namibia and is also exported. The European Union is Namibia’s <a href="http://www.seaflowergroup.com.na/wp-content/uploads/2018/08/Annual-Report-2017.pdf">largest</a> seafood export market. The fact that it’s a top predator increases its chance of accumulating mercury because, as <a href="https://pdfs.semanticscholar.org/f380/b3848c02678af9e18cf22aa1befcc107c8d7.pdf">research shows</a>, moving up the food chain, the mercury will accumulate and increase.</p>
<p>Cape monkfish also have long life spans: over <a href="https://www.researchgate.net/publication/258205860_Assessment_of_the_monkfish_Lophius_vomerinus_resource_off_Namibia">10 years</a>. </p>
<p>Our research compared the total mercury concentration between Cape monkfish muscle and liver tissue. We also related the mercury concentrations to the fish’s body size, depth and capture location. </p>
<p>We collected a total of 529 specimens of Cape monkfish from the three size classes; juveniles, sub-adults and adults, between 2016 and 2018. To check our laboratory results, we compared 50% of them with those obtained by the Namibian Standards Institution. </p>
<p>To establish whether the mercury concentration was spread evenly throughout a fish’s body we compared the concentration in its muscles and its liver tissue.</p>
<p>We found no significant difference in the two tissues. This implies that the muscle and liver tissues of Cape monkfish have statistically similar abilities to retain mercury. We expected significant differences because liver and muscles have different rates of metabolism. </p>
<p>The liver functions as a main storage organ and a <a href="https://www.researchgate.net/publication/258150247_Assessment_of_Aquatic_Pollution_Using_Histopathology_in_Fish_as_a_Protocol">detoxification site</a> so we expected the liver tissues to contain higher mercury concentrations than the muscle tissues. </p>
<p>We did find that juvenile fish had lower contamination than bigger and older fish. This suggests that as the fish grows, the total mercury concentration increases. It also means that older fish are more threatened by mercury compared to younger fish. </p>
<p>We also found differences in concentration based on the location of the fish. One differentiator was lines of latitude: fish caught from areas around 19⁰S, 20⁰S and 26⁰S off the coast of Namibia had higher mercury levels than those caught in other areas off the Namibian coast. This might imply that there are mercury hotspots along these latitudes where sources of mercury are high, which can be linked to elevated industrial activities especially at 20°S and 26°S which a closer to the industrial towns of Walvisbay and Lüderitz respectively.</p>
<p>The concentration of total mercury in Cape monkfish was significantly higher in deeper water, though still similar in muscle and liver tissues. </p>
<h2>What now?</h2>
<p>When buying Cape monkfish to eat, consumers should bear in mind that the bigger the fish, the more likely it is to have a high concentration of mercury. Mercury can potentially be <a href="https://www.sciencedirect.com/science/article/pii/S1470160X19305345">toxic</a> to people when consumed. These <a href="https://www.sciencedirect.com/science/article/pii/S0308814612005821">threats</a> may include renal failure, liver damage, cardiovascular diseases and even death. </p>
<p>Our findings should also be used to guide action taken by fishing companies operating around the 19⁰, 20⁰ and 26⁰S lines of latitude off the coast of Namibia. Fish caught from these areas should be screened for mercury and other heavy metals. </p>
<p><em>Johnny Gamatham and Stephanus Hamutenya also contribted to this article.</em></p><img src="https://counter.theconversation.com/content/125585/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Victoria Ndinelago Erasmus is affiliated with National Marine Information and Research Centre (NatMIRC), Ministry of Fisheries and Marine Resources, Namibia and Department of Ichthyology and Fisheries Science, Rhodes University, South Africa. </span></em></p><p class="fine-print"><em><span>Johannes Angala Iitembu for the University of Namibia. He receives funding from UNAM</span></em></p>Cape monkfish caught from some areas off Namibia’s coast should be screened for mercury and other heavy metals.Victoria Ndinelago Erasmus, PhD student, Rhodes UniversityJohannes Angala Iitembu, Senior Lecturer, Fisheries and Aquatic Sciences, University of NamibiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1185792019-06-13T18:42:29Z2019-06-13T18:42:29ZSeaweed and sea slugs rely on toxic bacteria to defend against predators<figure><img src="https://images.theconversation.com/files/279245/original/file-20190612-32317-1vvu0d3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Coral reefs contain an intricate web of predators and prey.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/wildlife-coral-natural-1074364064?studio=1">lisnic/Shutterstock.com</a></span></figcaption></figure><p>Plants, animals and even microbes that live on coral reefs have evolved a rich variety of defense strategies to protect themselves from predators. Some have physical defenses like spines and camouflage. Others have specialized behaviors – like a squid expelling ink – that allow them to escape. Soft-bodied or immobile organisms, like sponges, algae and sea squirts, often defend themselves with noxious chemicals that taste bad or are toxic. </p>
<p>Some animals that can’t manufacture their own chemical weapons feed on toxic organisms and steal their chemical defenses, having evolved resistance to them. One animal that does this is a sea slug that lives on the reefs surrounding Hawaii and dines on toxic <em>Bryopsis</em> algae. Marine scientists suspected the toxin is made by a bacterium that lives within the alga but have only <a href="https://science.sciencemag.org/cgi/doi/10.1126/science.aaw6732">just discovered the species</a> responsible and teased apart the complex relationship between slug, seaweed and microbe. </p>
<p>Ultimately, noxious chemicals allow predators and prey to coexist on coral reefs, increasing their diversity. This is important because diverse ecosystems are more stable and resilient. A greater understanding of the drivers of diversity will aid in reef management and conservation. </p>
<p>As marine scientists, we too study chemical defenses in the ocean. Our laboratory group at the <a href="http://devwp.kubanek.biology.gatech.edu/">Georgia Institute of Technology</a> explores how marine organisms use chemical signaling to solve critical problems of competition, disease, predation and reproduction. That’s why we were particularly excited by the discovery of this new bacterial species. </p>
<h2>Origins of a chemical defense</h2>
<p>In a <a href="https://science.sciencemag.org/cgi/doi/10.1126/science.aaw6732">report published in the journal Science</a>, researchers at <a href="https://scholar.princeton.edu/donialab/home">Princeton University</a> and the <a href="https://www.umces.edu/russell-hill">University of Maryland</a> discovered that a group of well-studied toxic defense chemicals, the <a href="https://doi.org/10.1021/jo960877+">kahalalides</a>, are actually produced by a <a href="https://science.sciencemag.org/cgi/doi/10.1126/science.aaw6732">bacterium that lives inside the cells of a particular species of seaweed</a>.</p>
<p>The scientific community had long speculated that a bacterium might be responsible for producing the kahalalides. So the discovery of the kahalalide-producing bacteria – belonging to the class Flavobacteria – has solved a long-standing scientific mystery. </p>
<p><em>Bryopsis</em> provides the bacteria with a safe environment and the chemical building blocks necessary for life and to manufacture the kahalalides. In return, the bacterium produces the toxins for the algae, which protect them from hungry fish scouring the reefs. But the seaweed isn’t the only organism that benefits from this arrangement. </p>
<p>The kahalalides, <a href="https://doi.org/10.1021/ja00066a061">originally discovered in the early 1990s</a>, also protect a sea slug, <em>Elysia rufescens</em>, that consumes it. The sea slugs accumulate the toxins from the algae, which then <a href="https://doi.org/10.1023/A:1012287105923">protects them from predators</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/279403/original/file-20190613-32366-17d1jo9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/279403/original/file-20190613-32366-17d1jo9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279403/original/file-20190613-32366-17d1jo9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=175&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279403/original/file-20190613-32366-17d1jo9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=175&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279403/original/file-20190613-32366-17d1jo9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=175&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279403/original/file-20190613-32366-17d1jo9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=220&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279403/original/file-20190613-32366-17d1jo9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=220&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279403/original/file-20190613-32366-17d1jo9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=220&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">William Harper Pease’s color drawing of <em>Elysia rufescens</em> featured in his original description of the species in 1871.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Elysia_rufescens">https://en.wikipedia.org/wiki/Elysia_rufescens</a></span>
</figcaption>
</figure>
<p>The discovery of a symbiosis between a bacterium and a seaweed to produce a chemical defense is noteworthy. There are many examples of bacteria living inside the cells of invertebrate animals (like sponges) and manufacturing toxic chemicals, but a partnership involving a <a href="https://science.sciencemag.org/cgi/doi/10.1126/science.aax8964">bacterium living in the cells of a marine seaweed</a> to produce a toxin is unusual. </p>
<p>The finding adds a new dimension to our understanding of the types of ecological relationships that produce the chemicals shaping coral reef ecosystems. </p>
<h2>The medicinal potential of toxins</h2>
<p>Our lab is home to an enthusiastic multidisciplinary team of marine chemists, microbiologists and ecologists who strive to understand how chemicals facilitate interactions between species in the marine environment. </p>
<p>We also use ecological insights to guide discovery of novel pharmaceuticals from marine organisms. Chemicals used by marine organisms to interact with their environment, including toxins which protect them from predators, often show promising <a href="https://www.ingentaconnect.com/contentone/scs/chimia/2017/00000071/00000010/art00002?crawler=true&mimetype=application/pdf">medical applications</a>. In fact, the most toxic kahalalide, kahalalide F, has been the focus of clinical trials for the <a href="https://doi.org/10.1021/cr100187n">treatment of cancer and psoriasis</a>. </p>
<p>Currently, we conduct our fieldwork in Fiji and the Solomon Islands in collaboration with a research group led by <a href="https://www.usp.ac.fj/index.php?id=18023">Katy Soapi</a> at the University of the South Pacific. There you can find us scuba diving to conduct ecological experiments or to collect algae and coral microbes to bring back for study in the laboratory.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/279253/original/file-20190612-32331-h301hu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279253/original/file-20190612-32331-h301hu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279253/original/file-20190612-32331-h301hu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279253/original/file-20190612-32331-h301hu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279253/original/file-20190612-32331-h301hu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279253/original/file-20190612-32331-h301hu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279253/original/file-20190612-32331-h301hu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Julia Kubanek collects samples during fieldwork in Fiji.</span>
<span class="attribution"><span class="source">Julia Kubanek</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>During the course of our field work we have had the opportunity to observe <em>Bryopsis</em> and have been struck by how lovely it is, standing out with its bright green color against the pinks, grays, browns and blues of a coral reef.</p>
<p>The story of the kahalalides is a good reminder that even though seaweed-associated bacteria may be invisible to the human eye and to fish predators, microbes and their chemicals play an important role in shaping coral reef structure and diversity, by allowing organisms to thrive in the face of predation.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/279256/original/file-20190612-32317-1o1h7ce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279256/original/file-20190612-32317-1o1h7ce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279256/original/file-20190612-32317-1o1h7ce.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279256/original/file-20190612-32317-1o1h7ce.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279256/original/file-20190612-32317-1o1h7ce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279256/original/file-20190612-32317-1o1h7ce.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279256/original/file-20190612-32317-1o1h7ce.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Fijian coral reef contains a vast collection of species, some filled with unknown toxic compounds.</span>
<span class="attribution"><span class="source">Julia Kubanek</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/118579/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samantha Mascuch receives funding from the National Science Foundation and the National Institutes of Health. </span></em></p><p class="fine-print"><em><span>Julia Kubanek receives funding from the National Science Foundation, the National Institutes of Health and Sandia National Laboratories. </span></em></p>Researchers have just discovered a new species of bacteria that cranks out a deadly toxin. In a common arrangement in the marine environment, a slug and alga both use this toxin for their own defense.Samantha Mascuch, Postdoctoral Fellow of Biological Sciences, Georgia Institute of TechnologyJulia Kubanek, Professor and Associate Dean of Biological Sciences, Georgia Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1177652019-05-29T13:40:23Z2019-05-29T13:40:23ZHow we found out that rat poisons are killing wildlife in Cape Town<figure><img src="https://images.theconversation.com/files/276784/original/file-20190528-42576-1ohldel.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Caracals that feed on poisoned rodents in Cape Town pass the toxins onto their young through contaminated milk. </span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Wildlife near cities face many dangers. Some are easy to detect, such as when new developments destroy natural habitat. Others are less obvious. </p>
<p>For example, rat poisons are a useful tool for controlling a common household problem. But many who use them don’t realise that they have dangerous side effects for wildlife. </p>
<p>Rat poisons are designed to work slowly in their target species, rats, so that they ingest lethal doses of the poisons. The rats then become sick and increasingly toxic over a period of days or weeks. Poisoned rats then become easy, highly toxic prey for predators. </p>
<p>The side effects of exposure to these poison compounds are especially worrying for local wildlife in Cape Town, South Africa. The city is situated within a global biodiversity hotspot that includes the world-renowned Table Mountain National Park. Here, with thousands of plant species already <a href="https://www.sanparks.org/parks/table_mountain/conservation/heritage.php">threatened</a> by habitat loss and modification, the poisoning of numerous predatory wildlife species that help retain ecosystem stability could disrupt the delicate ecological balance. </p>
<p>Using samples from seven species, scientists from the <a href="http://www.icwild.uct.ac.za/">Institute for Communities and Wildlife in Africa</a> at the University of Cape Town <a href="https://www.sciencedirect.com/science/article/pii/S0048969719306047#">investigated</a> just how frequently Table Mountain’s wild predators are exposed to rat poisons through their prey. </p>
<p>We detected five different commercially available rat poisons in the livers of 81% of the predators we tested. Predators included common ones such as genets, Cape Eagle owls, and water mongooses, and rarer ones such as caracals, otters, and a honey badger. The detection of rat poison in otters is especially interesting because it suggests that poisons used on land can make their way into the city’s streams, wetlands and estuaries. </p>
<p>Some wildlife species are already threatened by habitat loss, vehicle collisions, poaching, disease, and fire. Rat poisons make these populations even more vulnerable to local extinction. When many species are affected within a single ecosystem, the effects of the poison exposure can escalate to threaten the functioning of an entire ecosystem. </p>
<p>The finding of widespread toxic exposure to rat poison in Cape Town’s wildlife echo those for predatory species elsewhere in Europe and North America, such as <a href="https://www.ncbi.nlm.nih.gov/pubmed/29438955">polecats</a>, <a href="https://link.springer.com/article/10.1007/s00244-012-9771-6">owls and raptors</a>, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1523-1739.2003.01458.x">coyotes</a>, <a href="https://digitalcommons.lmu.edu/cgi/viewcontent.cgi?article=1144&context=cate">endangered kit foxes</a>, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040163">fishers</a>, and <a href="https://www.ncbi.nlm.nih.gov/pubmed/25707484">bobcats</a>. For some of these species, anticoagulants are named as a leading cause of death and are even linked with at least one dramatic population decline in a species similar to caracals, the North American <a href="https://www.ncbi.nlm.nih.gov/pubmed/29343604">bobcat</a>. Researchers fear a similar fate for wildlife near Cape Town. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/276783/original/file-20190528-42565-d6wf74.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/276783/original/file-20190528-42565-d6wf74.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/276783/original/file-20190528-42565-d6wf74.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/276783/original/file-20190528-42565-d6wf74.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/276783/original/file-20190528-42565-d6wf74.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/276783/original/file-20190528-42565-d6wf74.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/276783/original/file-20190528-42565-d6wf74.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A study conducted in Cape Town found that 92% of caracals had rat poisons in their livers.</span>
<span class="attribution"><span class="source">Provided by author</span></span>
</figcaption>
</figure>
<h2>Multiple species exposed to rat poisons</h2>
<p>In vertebrates – animals that have a backbone or spinal column – the liver is the organ responsible for removing toxins from the blood. This is where we looked for evidence of rat poison exposure. One challenge was that testing the liver meant we could only sample animals that were already dead, limiting how many animals we could assess. </p>
<p>To better understand how Cape Town’s local predators come into contact with poisoned rats, we explored the rich <a href="http://www.urbancaracal.org/publications">data</a> set of the <a href="http://www.urbancaracal.org/">Urban Caracal Project</a>, which included liver samples from 24 caracals. </p>
<p>Alarmingly, 92% of caracals had rat poisons in their livers. But the amount of poison in their livers varied. Caracals that frequented vineyards had the highest levels. This may be because vineyards allow caracals a safe space to hunt close to the urban edge – where rat poisons are widespread. </p>
<p>But rat poisons are also affecting caracals that have never even seen a rodent. Our analysis also revealed a caracal kitten as having very high levels of poisons. It appears that mothers may inadvertently poison their own young through contaminated milk.</p>
<h2>A widespread problem</h2>
<p>With greater economic opportunities in cities, rapid urbanisation is a reality. The challenges of managing waste and the animals it attracts, are rapidly mounting. </p>
<p>Using poisons is quick but dirty from a wildlife perspective: the ultimate price will be paid by those animals at the top of the peri-urban food chain, such as leopards and caracals. </p>
<p>Raising awareness about this is the first step. Ensuring the conservation of urban wildlife needs changes in the way that people understand their individual impact on local ecosystems. </p>
<p>As consumers, people need more eco-friendly alternatives to rat poison. Nevertheless, the simplest solution is well within everyone’s reach: improve the management of waste which attracts rats in the first place. </p>
<p>Households can make a choice about whether they use poisons in or around their homes. In other parts of the world similar research <a href="https://www.ncbi.nlm.nih.gov/pubmed/25707484">findings</a> have galvanised the public and spurred <a href="https://www.cdpr.ca.gov/docs/registration/reevaluation/2018_investigation_anticoagulant.pdf">regulations</a> on the use of these poisons. </p>
<p>We hope these research findings will stimulate a similar dialogue with home owners, businesses, and municipal authorities on how to reduce environmental contamination by rat poisons and other toxins in Cape Town and beyond.</p><img src="https://counter.theconversation.com/content/117765/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laurel Serieys receives funding from the University of Cape Town. Additional funding to support her research has come from the Claude Leon Foundation, private donors, Experiment Crowd Funding, Stellenbosch University, the University of California, Los Angeles, and the Cape Leopard Trust</span></em></p><p class="fine-print"><em><span>Jacqueline Bishop receives funding from the University of Cape Town and the South African National Research Foundation. </span></em></p>Household rat poison is endangering caracals, and other wildlife species in Cape Town, that prey on poisoned rodents. If not managed, this can negatively alter the region’s ecosystem.Laurel Serieys, Postdoctoral Fellow - University of California and Institute for Communities and Wildlife, University of Cape TownJacqueline Bishop, Senior Lecturer in Conservation Genetics, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1129952019-03-08T11:44:13Z2019-03-08T11:44:13ZOpium, rat hair, beaver anal secretions – and other surprising things you might find in food<figure><img src="https://images.theconversation.com/files/262923/original/file-20190308-155514-m6r0h8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1007022697?size=medium_jpg">Ranta Images/Shutterstock</a></span></figcaption></figure><p>Diners in France recently got more than they bargained for when poppy seed baguettes were found to contain a <a href="https://www.telegraph.co.uk/news/2019/03/03/french-poppy-seed-bread-found-contain-dangerous-levels-opium/">dose of opium</a> that could take postprandial napping to a new extreme. Other than narcotics, there are a host of surprises lurking in everyday foodstuffs that you might not be aware of. Here are some of the less palatable ones. Bon appétit.</p>
<p>When it comes to food, “natural” is usually a byword for “good”. But some natural products are a bit disgusting. For example, a natural flavouring called castoreum is a thick, odorous secretion obtained from the <a href="https://chestofbooks.com/animals/zoology/Anatomy/Mammalia-Part-22.html">anal glands of beavers</a>. It is used to give a vanilla flavour to some dairy products and desserts. </p>
<p>Towards the end of the 19th century, beavers were nearly hunted to extinction to acquire this highly desirable food additive and fragrance. Fortunately, <a href="https://translate.google.co.uk/translate?hl=en&sl=de&u=http://www.chemie.de/lexikon/Wilhelm_Haarmann.html&prev=search">German chemists</a> discovered that vanillin (one of the chemicals responsible for the taste of vanilla) could be extracted from the humble conifer. </p>
<p>Today, synthetic vanillin accounts for about 94% of all vanilla flavouring used in the food industry (<a href="https://globenewswire.com/news-release/2019/02/26/1742696/0/en/Global-Vanilla-and-Vanillin-Market-Trends-Share-Size-Growth-Opportunity-and-Forecast-Report-2019-2024.html">37,286 tons</a>), with natural vanilla extract accounting for most of the remaining 6%. Beavers can heave a sigh of relief. Their contribution to the food industry now accounts for a tiny fraction of natural vanilla flavouring and tends to be limited to luxury foods and beverages.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/262882/original/file-20190308-150673-1e1mjw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262882/original/file-20190308-150673-1e1mjw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262882/original/file-20190308-150673-1e1mjw4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262882/original/file-20190308-150673-1e1mjw4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262882/original/file-20190308-150673-1e1mjw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262882/original/file-20190308-150673-1e1mjw4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262882/original/file-20190308-150673-1e1mjw4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Luxury ice cream maker.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/645286162?size=medium_jpg">milmed/Shutterstock</a></span>
</figcaption>
</figure>
<p>Another natural ingredient that might make you retch is rennet. It traditionally came from the mucous membrane of the fourth stomach (<a href="https://en.wikipedia.org/wiki/Abomasum">abomasum</a>) of young ruminants, such as calves, lambs and goats. The enzymes separate milk into curds and whey – a key stage in the manufacturing process. </p>
<p>Traditional rennet is still used today, although alternatives (derived from mould, bacterial fermentation and plants such as nettles and ivy) are increasingly common, if not slightly more palatable.</p>
<h2>Allowable food defects</h2>
<p>We live in an era of unprecedented hygiene and expect our food to contain only the ingredients labelled on the packaging. But anyone who has foraged in the wild will know that nature likes to share its rich bounty. There is nothing surprising about taking a bite out of a freshly picked apple to find the remaining half of a (presumably very upset) insect. </p>
<p>Our basic foodstuffs are not grown in sterile conditions and so our diet is peppered with a variety of unintended side dishes, including soil, rodent hairs, faeces, mould, parasites and, of course, insects. The earthy nature of food production is acknowledged in the US through the publication of the <a href="https://www.fda.gov/food/guidanceregulation/guidancedocumentsregulatoryinformation/sanitationtransportation/ucm056174.htm">Defect Levels Handbook</a> that defines acceptable (non-hazardous) levels of these undisclosed morsels.</p>
<p>For example, two cupfuls of cornmeal may legitimately contain up to five whole insects, ten insect fragments, ten rodent hairs and five rodent poop fragments. It certainly puts that half-eaten apple into perspective.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/262885/original/file-20190308-150693-2luclp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262885/original/file-20190308-150693-2luclp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262885/original/file-20190308-150693-2luclp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262885/original/file-20190308-150693-2luclp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262885/original/file-20190308-150693-2luclp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262885/original/file-20190308-150693-2luclp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262885/original/file-20190308-150693-2luclp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An acceptable number of dead insects in two cupfuls of cornmeal.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1178986543?size=medium_jpg">oatpost/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Pollution – heavy metal</h2>
<p>Lewis Carroll’s fictional <a href="https://en.wikipedia.org/wiki/Alice%27s_Adventures_in_Wonderland">Mad Hatter</a> character may have been inspired by an occupational disease of milliners (hat makers) caused by exposure to mercury and its salts during a process called “<a href="https://en.wikipedia.org/wiki/Felt">carroting</a>”. </p>
<p>This was commonly used on the pelts of small animals, such as beavers, to make the fur softer. Beavers clearly didn’t have a good time in the 19th century, but the effects of mercury on milliners was equally devastating, with up to half the working population afflicted by <a href="https://en.wikipedia.org/wiki/Erethism">erethism</a>, or “mad hatters disease”, the signs and symptoms of which included irritability and excitability, muscle spasms, loss of teeth, nails and hair, lack of coordination, confusion, memory loss and death. </p>
<p>While phased out from most industrial processes, mercury remains a significant air and water pollutant. Indeed, the release of industrial waste into the sea off the south coast of Japan resulted in the local population eating seafood containing methylmercury, the most toxic form of mercury. Because of this, several thousand people became victims of <a href="https://en.wikipedia.org/wiki/Minamata_disease">Minamata disease</a>. </p>
<p>How did the seafood become so poisonous? The answer lies in an effect called <a href="https://www.bbc.com/bitesize/guides/zxgn97h/revision/5">bioaccumulation</a>, the process whereby the concentration of a substance can substantially increase with each step up the food chain (see illustration). So next time you tuck into a tuna steak, try not to get too irritable or excitable about the hidden mercury.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/262642/original/file-20190307-82695-e8mz4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262642/original/file-20190307-82695-e8mz4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262642/original/file-20190307-82695-e8mz4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262642/original/file-20190307-82695-e8mz4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262642/original/file-20190307-82695-e8mz4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262642/original/file-20190307-82695-e8mz4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262642/original/file-20190307-82695-e8mz4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Illustration of how methylmercury becomes more concentrated as it passes up the food chain. In this example, the concentration of methylmercury is expressed relative to seawater (given an arbitrary value of one). It can be seen that methylmercury is 10,000 times more concentrated in the top predator (tuna fish). Data from Harding, Dalziel and Vass.</span>
</figcaption>
</figure>
<h2>Natural contaminants</h2>
<p>Although pollutants like mercury, lead, cadmium and arsenic often make headlines as food contaminants, nature’s larder can accidentally contain a whole host of toxins. Many members of the rhododendron genus of flowering plants secrete grayanotoxins in their nectar. These neurotoxic substances are dutifully collected by bees who proceed to make honey, consumption of which can cause “mad honey disease” in humans. This rather unusual form of contamination can cause hallucinations, nausea and vomiting. </p>
<p>When we think of food poisoning, flowers rarely spring to mind, but rhododendron has been indirectly responsible for incapacitating entire <a href="https://www.zmescience.com/other/feature-post/mad-honey-deli-bal/">armies</a>. True flower power!</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/262884/original/file-20190308-150697-840pjh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262884/original/file-20190308-150697-840pjh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262884/original/file-20190308-150697-840pjh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262884/original/file-20190308-150697-840pjh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262884/original/file-20190308-150697-840pjh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262884/original/file-20190308-150697-840pjh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262884/original/file-20190308-150697-840pjh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Rhododendron, destroyer of armies.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/536510839?size=medium_jpg">Ottochka/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Natural born killers</h2>
<p>Pickles and preserves have been used for centuries to extend the shelf life of food through the winter months. Unfortunately, badly preserved food can encourage the growth of <em>Clostridium botulinum</em>, which produces the world’s most toxic substances, collectively known as <a href="https://www.who.int/news-room/fact-sheets/detail/botulism">botulinum toxin</a>, some of which can be fatal at a dose of 2ng – that’s two thousand millionths of a gram. To put that in perspective, the average lethal dose of potassium cyanide is about a tenth of a gram. </p>
<p>Eating contaminated food will cause <a href="https://www.nhs.uk/conditions/botulism/">botulism</a>, which stops the nervous system functioning properly. Correspondingly, the condition is characterised by general muscle weakness and, eventually, paralysis and death.</p>
<p>Spores of <em>C. botulinum</em> are often found in honey. While relatively harmless to most people, the immune system of young infants is relatively ineffective against these bacteria, which can lead to a related condition known as infantile botulism. Indeed, this is why many government agencies advise against giving honey to children under a year old.</p><img src="https://counter.theconversation.com/content/112995/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Chilcott does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>It doesn’t always pay to know what’s really in your food – but it’s fun to find out, anyway.Robert Chilcott, Professor, Centre for Research into Topical Drug Delivery and Toxicology, University of HertfordshireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1121072019-03-06T15:00:04Z2019-03-06T15:00:04ZMystery of French babies born with deformed arms – here’s what a developmental biologist thinks<figure><img src="https://images.theconversation.com/files/262400/original/file-20190306-100772-xxb1sf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/403103896?size=medium_jpg">bogonet/Shutterstock</a></span></figcaption></figure><p>REMERA, a French national birth-defect registry, recently identified clusters of children born with malformed limbs in three rural regions in <a href="https://www.thelocal.fr/20181031/11-more-cases-of-babies-born-with-missing-arms-in-france">France</a>. Each cluster has three to eight children with malformations that include children with missing or deformed arms and hands.</p>
<p>The French public health department (Santé Publique France) originally suggested that these cases were not above what was naturally expected each <a href="https://www.theguardian.com/world/2018/oct/08/france-doctors-fail-solve-mystery-babies-missing-limbs">year</a>. Around 3-4% of children, worldwide, have a <a href="https://genetics.emory.edu/documents/resources/Emory_Human_Genetics_General_Population_Risk_for_Birth_Defects.PDF">birth malformation</a>. Although genetic, chromosomal and environmental causes – such as medicines – can account for some of these malformations, in most cases the cause is unknown.</p>
<p>It is difficult to know if the type and number of these limb differences in France are to be expected or if they are cause for concern. This is made more difficult by the fact that the French birth-defects registry only covers <a href="https://med.news.am/eng/news/21245/parents-demand-answers-after-mysterious-birth-defect-leaves-more-than-20-french-babies-without-arms.html">19% of the country’s births</a>. </p>
<p>However, Santé Publique France has now established a <a href="https://www.france24.com/en/20190221-france-baby-babies-born-arm-upper-limb-reduction-defect-remera-spf">formal panel</a> to investigate these cases and determine the cause, probably in response to <a href="https://med.news.am/eng/news/21245/parents-demand-answers-after-mysterious-birth-defect-leaves-more-than-20-french-babies-without-arms.html">pressure</a> from the public to find answers.</p>
<h2>Looking for causes</h2>
<p>Exactly how limb defects come about is still not fully understood, but we do know they are linked to exposure to certain drugs, such as <a href="https://theconversation.com/thalidomide-the-drug-with-a-dark-side-but-an-enigmatic-future-50330">thalidomide</a>, as well as <a href="https://www.cdc.gov/ncbddd/birthdefects/ul-limbreductiondefects.html">industrial pollutants</a> – as was the case in <a href="http://news.bbc.co.uk/1/hi/england/northamptonshire/8624828.stm">Corby</a>, England in the 1990s.</p>
<p>Genetic influences are a potential cause, though this appears to have been ruled out by <a href="https://www.thelocal.fr/20181031/the-story-behind-the-high-number-of-babies-in-france-born-without-arms">REMERA</a> as the children’s families did not have similar problems in previous generations. </p>
<p>Of course, spontaneous mutations in genes involved in limb formation could be the cause, but these events are rare. The fact that it occurred in several children causing similar damage in three different rural areas of France makes this theory unlikely.</p>
<p>REMERA has proposed that the limb malformations could result from exposure to environmental pollutants and toxins, which could include <a href="https://www.thelocal.fr/20181031/the-story-behind-the-high-number-of-babies-in-france-born-without-arms">pesticides and herbicides</a> that are used on nearby <a href="https://www.sott.net/article/399595-Pesticides-France-launches-another-probe-after-more-birth-defects-cases-revealed">farms</a>. This may be a credible theory as herbicides, such as <a href="https://www.ncbi.nlm.nih.gov/pubmed/20695457">glyphosate</a>, have been shown to cause limb malformations in frog embryos in laboratory experiments.</p>
<p>Also, insecticides, such as methoprene, that have contaminated ponds in the wild have been <a href="https://www.ncbi.nlm.nih.gov/pubmed/12763670">linked</a> to malformed limbs in wild frogs in the US and Canada. </p>
<p>Laboratory tests show that these compounds can convert into a <a href="https://www.ncbi.nlm.nih.gov/pubmed/20695457">retinoic-acid-like molecule</a>. Retinoic acid comes from vitamin A and is very important in embryonic development. Exposing mink frog embryos to retinoic acid in lab tests resulted in a <a href="https://www.ncbi.nlm.nih.gov/pubmed/10404649">range of damage</a> to the embryos. </p>
<p>These facts suggest that agricultural chemicals, getting into the water supply or food chain, could influence embryonic development and result in damage. But more work is needed before we can be sure that these chemicals cause limb malformations in humans.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/262405/original/file-20190306-100775-13vvsqc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262405/original/file-20190306-100775-13vvsqc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262405/original/file-20190306-100775-13vvsqc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262405/original/file-20190306-100775-13vvsqc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262405/original/file-20190306-100775-13vvsqc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262405/original/file-20190306-100775-13vvsqc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262405/original/file-20190306-100775-13vvsqc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Could agricultural chemicals be to blame?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/348615704?size=medium_jpg">Fotokostic/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Unilateral limb defect</h2>
<p>Perhaps what is most striking about the reported French cases is that many of the children have <a href="https://www.cdc.gov/ncbddd/birthdefects/ul-limbreductiondefects.html">defects</a> to just one arm. This is called a unilateral limb defect. How unilateral limb differences come about is poorly understood.</p>
<p>Recent research shows that the right and left arms may have differences in some of the genes involved in ensuring the arms form correctly and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5215935/">symmetrically</a>. We also know that retinoic acid can control some of the genes involved in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5215935/">forming limbs</a>.</p>
<p>The effect of insecticides, pesticides and herbicides on human health is also poorly understood. We know some can cause cancer – though how they do this is unclear. Given that some herbicides and insecticides appear to be able to affect retinoic acid signalling, which is needed to control gene activity in the embryo, it might help explain the unilateral limb differences.</p>
<p>It cannot be ruled out these clusters could simply be random events and within the range of what is to be expected naturally. However, this seems difficult to confirm with incomplete birth-defect records. Given the reported use of pesticides and herbicides in the cluster areas, all lines of investigation should be kept open.</p><img src="https://counter.theconversation.com/content/112107/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Neil Vargesson would like to thank Emmanuelle Amar, Elisabeth Gnasia and members of REMERA for helpful discussions and information sharing regarding the clusters of children in France.
Neil Vargesson has received no funding for this article.</span></em></p>Possible causes of limb malformations in babies born in rural areas of France.Neil Vargesson, Professor in Developmental Biology, University of AberdeenLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1036252018-10-22T14:29:47Z2018-10-22T14:29:47ZCancer causing toxicants found in a tributary of South Africa’s second largest river<figure><img src="https://images.theconversation.com/files/241267/original/file-20181018-67176-tsbne9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A water bridge over the Klip River in Gauteng, South Africa.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p><em>A new <a href="https://www.sciencedirect.com/science/article/pii/S0048969718304650?via%3Dihub">study</a> has established that sharptooth catfish found in the Klip River which feeds into the Vaal River, South Africa’s second largest river, contains banned pesticides which can cause cancer when consumed by humans.</em></p>
<p><em>The river runs through high density residential areas, including Soweto, Lenasia and Fleurhof in the south of Johannesburg. Some residents supplement their diet by fishing the popular catfish in the rivers as well as dams fed by them. The Conversation Africa’s Nontobeko Mtshali asked Rialet Pieters to explain the implications of these findings.</em></p>
<p><strong>What are these banned pesticides?</strong></p>
<p>The pesticides we looked at are collectively known as organochlorine pesticides. They are used in agriculture to control insects that eat crops. </p>
<p>We did a human health risk assessment on the sharptooth catfish found in Orlando Dam and the Fleurhof and Lenasia areas in the south of Johannesburg. We chose this fish because it’s popular and widely consumed. The pesticides we targeted in the sharptooth catfish were lindane, heptachlor, aldrin, dieldrin, endrin and dichloro-diphenyl-trichloro-ethane (DDT). We found levels of heptachlor, DDT, and lindane in the fish. </p>
<p>All of the pesticides except for one, DDT, which is used against malaria-carrying mosquitoes, are banned in South Africa. So they should not be in the river. It’s not clear how they ended up in the Soweto, Fleurhof and Lenasia areas, though they could have made their way down the river from malaria-prone rural areas of the country.</p>
<p>The pesticides, with the exception of DDT, were banned by the international community under the <a href="http://chm.pops.int/">Stockholm Convention on Persistent Organic Pollutants</a> because of their harmful effects on the health of humans and wildlife. South Africa is a signatory to the convention and is obliged to reduce and eliminate the use of all the compounds <a href="http://chm.pops.int/TheConvention/ThePOPs/AllPOPs/tabid/2509/Default.aspx">listed in the convention</a>.</p>
<p>The DDT presence is unusual in an urban area because it’s mostly used in more rural settings to control mosquitoes and the spread of malaria.</p>
<p><strong>How bad are the pollution levels in the river that runs through Soweto, Fleurhof and Lenasia?</strong></p>
<p>We found the pesticides were present in fish tissue that we tested. DDT was the most prevalent at all the sites. The concentrations of the pesticides were at levels much higher than internationally accepted parameters. This suggests the fish pose a risk to human health because the compounds bio-accumulate in the fish and when people eat them they can potentially cause cancer.</p>
<p>There is <a href="http://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Evaluation-Of-Carcinogenic-Risks-To-Humans/Occupational-Exposures-In-Insecticide-Application-And-Some-Pesticides-1991">evidence</a> that the banned pesticides, as well as DDT, can cause a host of cancers such as lung, skin, bladder, and non-Hodgkin’s lymphoma, to name but a few. </p>
<p>We did a human health risk assessment using the concentrations of the pollutants in the fish to predict their effects in humans when consumed regularly. We collected 30 sharptooth catfish (one of several species of fish in the river) and determined the concentrations of DDT in the fillet. </p>
<p>We then calculated the chances of developing cancer for a human weighing 60 kg and eating 30 g of the contaminated fish every day. We followed the internationally standardised <a href="http://www.epa.gov/cancerguidelines/2005">calculations</a> and values for predicting human cancer risk. To account for the varying levels of pesticides in fish, cancer risk was calculated for the mid-range and high range pollutant level.</p>
<p>The probable cancer risk to DDT exposure varied between the three sites. The probability of developing cancer from eating the fish contaminated by DDT from Lenasia was the highest. We found that 251 out of 10 000 people may develop cancer if exposed to the mid-range level of the pesticide and 1 105 out of 10 000 people may develop cancer from the high range. At Fleurhof the risk ranged from 172 to 359 in 10 000 and at Orlando Dam from 191 to 624 in 10 000 people. </p>
<p>According to the US Environment Protection Agency, any risk greater than 1 in 10 000 is deemed an “unacceptable risk”. </p>
<p>We did not calculate the total cancer risk potentially posed by all the compounds together. Our focus was on DDT because of the high concentrations we found.</p>
<p><strong>What should be done to fix the problem?</strong></p>
<p>People who regularly eat or buy fish from the contaminated water need to be made aware of the risks to their health. One way of doing so is to have notice boards that advise on the safe consumption levels of the different species.</p>
<p>Fish from these areas need to be monitored regularly. And the sale of pesticides needs to be regulated better to ensure that the banned ones aren’t being traded.</p>
<p><em>Nico Wolmarans also contributed to this article.</em></p><img src="https://counter.theconversation.com/content/103625/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rialet Pieters receives funding from the Water Research Commission (K2/2242/1/16) of South Africa and the National Research Foundation</span></em></p><p class="fine-print"><em><span>Mayumi Ishizuka works at Hokkaido University. She receives funding from JSPS (Japan Society for the Promotion of Science). </span></em></p><p class="fine-print"><em><span>Nico Smit receives funding from South Africa's National Research Foundation (NRF). </span></em></p><p class="fine-print"><em><span>Ruan Gerber received funding from the Nation Research Foundation (NRF).</span></em></p><p class="fine-print"><em><span>Victor Wepener receives funding from the National Research Foundation (NRF), the Department of Science and Technology and the Flemish Inter University Council. </span></em></p><p class="fine-print"><em><span>Wihan Pheiffer receives funding from Water Research Commission (K2/2242/1/16) of South Africa and the National Research Foundation. </span></em></p><p class="fine-print"><em><span>Yared Beyene and Yoshinori Ikeneka do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Harmful pesticides have been found in the widely consumed sharptooth catfish found in a river that runs through Johannesburg.Rialet Pieters, Associate professor, North-West UniversityMayumi Ishizuka, Professor of Environmental Toxicology, Hokkaido UniversityNico J Smit, Director: Unit for Environmental Sciences and Management, North-West UniversityRuan Gerber, Postdoctoral fellow, North-West UniversityVictor Wepener, Director: School for Biological Science, North-West UniversityWihan Pheiffer, Senior Lecturer, DST/NWU Preclinical Drug Delivery Platform, North-West UniversityYared Beyene, Researcher, Faculty of Veterinary Medicine, Hokkaido UniversityYoshinori Ikeneka, Researcher, Faculty of Veterinary Medicine, Hokkaido UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/990202018-07-31T20:14:48Z2018-07-31T20:14:48ZWhat’s wrong with big solar in cities? Nothing, if it’s done right<figure><img src="https://images.theconversation.com/files/228975/original/file-20180724-76263-9i8ydz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Residents near big solar projects are often concerned they cause glare and noise.</span> <span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/2/26/Electrical_and_Mechanical_Services_Department_Headquarters_Photovoltaics.jpg">Electrical and Mechanical Services Department Headquarters rooftop solar, Hong Kong/Wikimedia Commons</a></span></figcaption></figure><p>Many of us are <a href="https://www.theguardian.com/environment/2015/mar/02/under-the-sun-australias-largest-solar-farm-set-to-sprout-in-a-queensland-field">familiar with developments</a> of big solar farms in rural and regional areas. These are often welcomed as a positive sign of our transition towards a <a href="https://theconversation.com/australia-can-get-to-zero-carbon-emissions-and-grow-the-economy-32015">low-carbon economy</a>. But do large-scale solar installations have a place in our cities? </p>
<p>The City of Fremantle in Western Australia is considering a proposal to use a former landfill site for a large-scale solar farm. The reportedly <a href="https://www.theaustralian.com.au/national-affairs/state-politics/council-faces-backlash-over-bid-for-fremantle-solar-farm/news-story/8d9842c63d35e41cc282fdbcb9978197">4.9 megawatt solar power station</a> on an eight-hectare site would be, it’s said, <a href="https://www.communitynews.com.au/fremantle-gazette/news/proposal-could-see-south-fremantle-become-site-of-largest-urban-solar-farm-in-australia/">Australia’s largest urban solar farm</a>. The initiative is part of Fremantle’s ambition to be powered by 100% clean energy <a href="http://citiespowerpartnership.org.au/partners/city-of-fremantle/">within a decade</a>.</p>
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<a href="https://theconversation.com/solar-is-now-the-most-popular-form-of-new-electricity-generation-worldwide-81678">Solar is now the most popular form of new electricity generation worldwide</a>
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<p>The proposal is facing some community opposition, however. <a href="https://www.theaustralian.com.au/national-affairs/state-politics/council-faces-backlash-over-bid-for-fremantle-solar-farm/news-story/8d9842c63d35e41cc282fdbcb9978197">Residents are reportedly alarmed</a> by the potential public health consequences of building on a rubbish dump, which risks releasing toxic contaminants such as asbestos into the environment. Other concerns include glare from the solar panels, or excessive noise. </p>
<p>Similar complaints about solar panels in cities are being seen <a href="https://www.scientificamerican.com/article/solar-panel-boom-pits-neighbor/">all over the world</a>, with opponents <a href="https://www.newsobserver.com/news/local/community/eastern-wake-news/ewn-opinion/article81653762.html">generally of the view</a> “they do not belong in residential areas”. So what are the planning issues associated with large-scale solar installations in cities? And should we be concerned about possible negative impacts?</p>
<h2>What is large-scale solar?</h2>
<p>According to the <a href="http://www.cleanenergyregulator.gov.au/RET/How-to-participate-in-the-Renewable-Energy-Target/eligibility-for-the-renewable-energy-target/defining-small-scale-and-large-scale-solar-systems">Australian Clean Energy Regulator</a>, large-scale solar refers to “a device with a kilowatt (kW) rating of more than 100 kilowatts”. A kilowatt is a measure of power – the rate of energy delivery at a given moment – whereas a kilowatt-hour (kWh) is a measure of the total energy produced (so a 100kW device operating for one hour would produce 100kWh of electricity).</p>
<p>Device here refers to not only the photovoltaic (PV) panels – the <a href="https://theconversation.com/explainer-what-is-photovoltaic-solar-energy-12924">actual panels</a> used in solar energy – but also to the infrastructure “behind the electricity meter”. So interconnected panels may still constitute a single device.</p>
<p>By this definition, there may already be large-scale solar installations in Australian cities. In Sydney for example, the recently opened system on top of the <a href="https://www.smh.com.au/business/the-economy/elon-musk-turns-sydney-transport-depot-into-green-energy-hub-20180627-p4zo1t.html">Alexandra Canal Transport Depot</a> is by all accounts a large-scale solar system. It combines around 1,600 solar panels with enough battery storage for 500kWh of electricity.</p>
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<a href="https://theconversation.com/sydneys-closer-to-being-a-zero-carbon-city-than-you-think-85976">Sydney's closer to being a zero-carbon city than you think</a>
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<p>But this is not Sydney’s largest solar installation. That honour is presently held by the <a href="https://www.smh.com.au/business/the-economy/sydney-markets-flicks-the-switch-on-massive-solar-installation-20180312-p4z3xr.html">Sydney Markets in Flemington</a>, among Australia’s largest rooftop solar installations, which generates around 3 megawatts (that’s 3,000kW). To date, there have been no publicly disclosed complaints received about these facilities.</p>
<p>Large-scale solar (<a href="https://theconversation.com/with-big-solar-australia-could-be-backing-a-winner-but-it-still-needs-leadership-47351">sometimes called “big solar”</a>) can also refer to <a href="https://www.cleanenergycouncil.org.au/technologies/large-scale-solar-PV.html">solar arrays that use mirrors</a> to concentrate sunlight onto solar PV panels. This is different to concentrated <a href="https://theconversation.com/with-a-bit-of-concentration-solar-thermal-could-power-your-town-2005">thermal solar</a>, which uses mirrors to focus sunlight onto the top of a tower to heat salt, oil or other materials that can then be used to generate steam to power turbines for electricity generation.</p>
<h2>What’s the problem with solar in cities?</h2>
<p>Internationally, there is increasing recognition <a href="https://grist.org/business-technology/we-could-put-utility-scale-solar-plants-in-our-cities/">cities could be ideal locations</a> for large-scale solar installations due to the amounts of unused land. This includes land alongside freeways and main roads, flood-prone land, and rooftops on factories, warehouses and residences. And locating big solar in cities can also <a href="http://insideenergy.org/2015/11/06/lost-in-transmission-how-much-electricity-disappears-between-a-power-plant-and-your-plug/">reduce the energy losses</a> that occur with transmitting electricity over long distances.</p>
<p>Australia’s combined rooftop solar installations already supply the equivalent of <a href="https://arena.gov.au/blog/rooftopsolar/">enough power for all the homes in Sydney</a>. And even <a href="https://www.ucsusa.org/clean-energy/renewable-energy/solar-power-plants-large-scale-pv#.W1Z4Oy1L2Lg">former landfill sites</a> – which have few uses other than parkland and are often too contaminated to sustain other land uses such as residential development – can be a good use of space for solar farms. But such sites would need to be carefully managed so contaminants are not released during construction.</p>
<p>Large-scale solar installations can present some challenges for urban planning. For instance, mirrors can cause problems with glare, or even damage if they were misaligned (<a href="https://www.wired.com/2016/05/huge-solar-plant-caught-fire-thats-least-problems/">problems thus far</a> have been in solar thermal plants). Maintenance vehicles may increase traffic in neighbourhoods. Installing solar panels could cause temporary problems with noise and lighting. And views could potentially be disrupted if adjoining residents overlook a large-scale solar installation.</p>
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Read more:
<a href="https://theconversation.com/pace-of-renewable-energy-shift-leaves-city-planners-struggling-to-keep-up-82206">Pace of renewable energy shift leaves city planners struggling to keep up</a>
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<p>But not all of these impacts would be long-term, and they can all potentially be managed through planning approval, permitting processes and development conditions. Installing screens or trees can improve views, for instance. Glare is a potential problem but again can be managed via screening (<a href="http://planning.cambridgeshire.gov.uk/swift/MediaTemp/42494-1950963160.pdf">at the site or on overlooking buildings</a>) or <a href="https://www.sciencedaily.com/releases/2014/04/140415084419.htm">protective films</a> on the panels.</p>
<p>The issue with the proposed solar farm in Fremantle is the fact it’s planned atop a former landfill site, known to contain harmful substances including asbestos, hydrocarbons and heavy metals. Unless carefully managed, construction of the solar farm could disturb these materials and potentially expose nearby residents to health impacts. </p>
<p>Most state environmental protection agencies recognise risks if the use of potentially contaminated land is to be changed, and have developed <a href="https://www.epa.vic.gov.au/your-environment/land-and-groundwater/contaminated-site-management">stringent guidelines</a> for landfill management.</p>
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<a href="https://images.theconversation.com/files/229166/original/file-20180724-194131-1gqfz2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/229166/original/file-20180724-194131-1gqfz2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/229166/original/file-20180724-194131-1gqfz2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/229166/original/file-20180724-194131-1gqfz2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/229166/original/file-20180724-194131-1gqfz2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/229166/original/file-20180724-194131-1gqfz2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/229166/original/file-20180724-194131-1gqfz2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/229166/original/file-20180724-194131-1gqfz2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The Algarve Lagos solar farm in Portugal shows how empty land in cities can be used to host energy efficiency platforms.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Portugal_-_Algarve_-_Lagos_-_solar_farm_(25504697990).jpg">Wikimedia Commons</a></span>
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<p>The City of Fremantle has <a href="https://mysay.fremantle.wa.gov.au/development-application-solar-farm">approved the proposed development</a>, subject to the preparation of a site management plan among other conditions. Depending on site management, and the characteristics of surrounding neighbourhoods, poorly managed big solar on landfill sites could become an <a href="https://theconversation.com/a-healthy-environment-shouldnt-just-be-for-the-rich-10439">environmental justice issue</a>. From this perspective, residents’ concerns are understandable, and the City of Fremantle will need to ensure it carefully monitors construction. </p>
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Read more:
<a href="https://theconversation.com/infrasound-phobia-spreads-to-solar-energy-cells-whats-next-46023">Infrasound phobia spreads ... to solar energy cells! What's next?</a>
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<h2>Lessons for planning</h2>
<p>It is reasonable to expect that cities will increasingly host large-scale solar installations. With careful site selection and management, the multiple benefits of clean energy can accrue to urban residents. Otherwise leftover or marginal land can derive an economic return.</p>
<p>Of course care will need to be taken to minimise <a href="https://www.scientificamerican.com/article/solar-farms-threaten-birds/">potential habitat loss</a> or off site impacts such as visual intrusion, noise, and glare. But solar farms also <a href="https://www.theguardian.com/environment/2016/mar/07/solar-farms-to-create-natural-habitats-for-threatened-british-species">have the potential to provide new habitats</a> both via physical infrastructure (sites for nesting) and as part of site rehabilitation and management.</p><img src="https://counter.theconversation.com/content/99020/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Byrne receives funding from the Australian Research Council for research on (i) climate change and social innovation and (ii) green space and health. He is a member of the Planning Institute Australia, Institute of Australian Geographers and Association of American Geographers. Jason donates to environmental groups (e.g. Australian Conservation Foundation). He also provides research consultancy services to state and local government.</span></em></p>Big solar has a potentially bright future in cities, but we need to get the planning right first.Jason Byrne, Professor of Human Geography and Planning, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/912522018-02-07T14:01:39Z2018-02-07T14:01:39ZWhy some fireflies become femme fatales in their race for survival<figure><img src="https://images.theconversation.com/files/205040/original/file-20180206-14083-tcllf7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">"Hello there, handsome..."</span> <span class="attribution"><span class="source">knoelle44/flickr</span></span></figcaption></figure><p>Fireflies are the flashy stars of the insect world. At night, you can see them coming because each little bug shines like a lamp – and, appropriately, they belong to the beetle family <a href="https://bugguide.net/node/view/85">Lampyridae</a>. </p>
<p>The “lamplight” of fireflies is generated by an enzyme inside the bugs’ abdomens called luciferase, which reacts with other elements and compounds to produce a cold light. This turns each individual firefly into a <a href="https://www.scientificamerican.com/article/how-and-why-do-fireflies/">bioluminescent</a> beauty.</p>
<p>Their glow is also used for courtship. Males of different firefly species use different <a href="http://science.sciencemag.org/content/187/4175/452">flash patterns</a> to <a href="http://www.annualreviews.org/doi/abs/10.1146/annurev.ento.53.103106.093346">attract potential mates</a>. A male firefly will flash in a certain pattern for a particular length of time; he knows whether the female he’s spotted is interested based on how long it takes her to “flash” in reply.</p>
<p>This all sounds very romantic and beautiful. But there’s a dark secret lurking behind the facade: some female fireflies dupe the males with false flash patterns – then, when their amorous would-be partners approach, they attack and eat them. The <a href="http://www.pnas.org/content/94/18/9723.short">femme fatales</a> aren’t doing this from malice or hunger: they’re trying to ingest a toxin that will keep them safe from predators.</p>
<h2>“Come closer…”</h2>
<p>This lethal mating ritual happens in two genera of fireflies, <a href="http://animaldiversity.org/accounts/Photinus_pyralis/"><em>Photinus</em></a> and <a href="http://animaldiversity.org/accounts/Photuris_versicolor/"><em>Photuris</em></a>. Both of the fireflies are native to North America.</p>
<p>The <em>Photuris</em> female is able to mimic <em>Photinus’</em> flashing patterns; with this deception, she answers the flash patterns of a <em>Photinus</em> male. He comes closer, hoping to consummate their new relationship. Instead, she captures and eats him.</p>
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<figcaption><span class="caption">Predation in fireflies: <em>Photuris versicolor</em> preys on <em>Photinus pyralis</em></span></figcaption>
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<p>Why? Because, as the saying goes, “You are what you eat.” In this case, the <em>Photuris</em> female eats the <em>Photinus</em> male to get chemical defences that are present in his blood. The toxins can be used to fight off <a href="https://www.hindawi.com/journals/psyche/2012/634027/">predators</a> like birds, spiders, ants and others.</p>
<p>When the <em>Photinus</em> male is under attack, the toxins are released as tiny droplets. By eating the male, the <em>Photuris</em> female absorbs that toxic power and makes herself safer from predation. The powerful toxins are called <a href="http://www.pnas.org/content/75/2/905.short">lucibufagins</a>, which are steroids similar to the heart poison generated from the <a href="https://www.aaas.org/blog/scientia/digitalis-flower-drug-poison">foxglove plant</a>, <em>Digitalis</em>. </p>
<p>When a firefly is attacked its outer skin, called the <a href="http://bugs.bio.usyd.edu.au/learning/resources/Entomology/internalAnatomy/cuticle.html">cuticle</a>, ruptures and bitter tasting blood loaded with lucibufagins oozes out. Predators release the firefly because they can’t stand the taste.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A firefly (<em>Photuris</em>) exuding the poisonous fluid from its body when disturbed.</span>
<span class="attribution"><span class="source">Thomas Eisner, 1997</span></span>
</figcaption>
</figure>
<h2>Avoidance tactics</h2>
<p>When a female <em>Photuris</em> eats a <em>Photinus</em> male and absorbs his lucibufagins, she is also protecting her young. The females are able to pass on this toxic defence mechanism <a href="http://www.pnas.org/content/94/18/9723.short">to their offspring</a>.</p>
<p>The <em>Photinus</em> males try to protect themselves from being eaten by <em>Photuris</em> females. They take their time looking for the real thing: a female of their own species. One study, in a laboratory <a href="https://books.google.com.np/books?hl=en&lr=&id=eHV_8YC_NL0C&oi=fnd&pg=PA113&dq=photinus+males+attempt+to+land+further+away+from+the+female+to+make+sure+that+she+is+of+the+same+species&ots=78t3MceGkQ&sig=Y4DrDTo6eL0-KtF9pZ6In9pZrCY&redir_esc=y#v=onepage&q&f=false">showed</a> that <em>Photinus</em> males took more than seven nights to find a female of its own species, while a <em>Photinus</em> female of the same species took less than six minutes to attract a male for mating. </p>
<p>The <em>Photinus</em> males also change their light emitting patterns in a bid to mislead their nemesis or – if they’re quick enough – simply fly away as soon as they are realise they’ve been drawn into a trap.</p><img src="https://counter.theconversation.com/content/91252/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Prayan Pokharel does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Beneath their beautiful, flashing facade some female fireflies are ruthless predators.Prayan Pokharel, Doctoral Student at the Institute for Insect Biotechnology, University of GiessenLicensed as Creative Commons – attribution, no derivatives.